Please correct me on details I have wrong -- before the edit timer runs out would be good. VolcanicGlass asked a question on the vidcaps topic so I did some homework. The post is buried in that topic, so thought I'd make it separate. We can update it as we go along, make comments on HII strategy, producer manipulation or not, and so forth.
-------
To begin, the list of the fooled who departed Idol in Pocket:
James (China), Ozzy, Jason (Micronesia), Brendan (Tocantins), and Erik (Samoa). Of these, I believe that only Erik's HII was a secret.
S11 GUATEMALA
The HII was introduced as a twist shortly after merge. HII clue came with reward, but Gary Hogeboom was able to find the HII without the clue by shadowing Judd. Gary did play it and saved himself for one time.
# of Idols, Locations, Clues, Twists, Expiration, Plays, Blindsides, Rehidden or not
S12 PANAMA EXILE ISLAND
The first season long HII was introduced with Exile Island. Only one HII, clue given to Exile. HII hidden at EI.
Twist: winning tribe of RC (or individual RC winner or team) picked exile from opposite tribe.
Expired F4
Terry found HII in Ep. 4. Never needed to play it, had immunity the episode it expired.
S13 COOK ISLANDS
Rules same as PEI.
One HII, clue given to Exile. HII hidden at EI.
Twist: winning tribe of RC (or individual RC winner or team) picked exile from opposite tribe.
Expired F4
Yul found HII in Ep 2, never needed to play it.
S14 FIJI
Clue was at EI, but there were two HII's, one in each camp.
Twist: RC winner picked Exile from opposing tribe.
Expired: F5
HII #1: Yau Man found HII Ep 7.
Yau played it at F6/Ep 13. First "idol bounce" ever.
HII #2: Edgardo/Alex/Mookie found it together in Ep 8.
HII #2 played by Alex Ep 10.
Idol rehidden.
Yau exiled himself to get clue at EI, shared with Earl. Earl found it at F6.
Earl played it at F5, expiring. (?)
S15 CHINA
No Exile Island, 2 idols, 1 in each camp, hidden in main part of camp.
Twist: RC winner got to kidnap a member of opposite tribe, who would have a clue to share. No clues given out post-merge as both had been found. Not clear how or if they planned to give them out, see Samoa for one method.
Expired: Most likely F5.
James voted out at F7 with 2 in pocket (one from Todd in Ep 6, one found in Ep 7. People knew he had them. No HII put back in play. Reason not given.
Jaime played an item she mistakenly thought was an idol.
S16 MICRONESIA (Fans vs. Faves)
1 HII, clue and idol at Exile Island, with one exception where only the clue was at EI.
Twists: Pre-merge RC winner chooses exile, then someone from winning tribe must go too. Both can use clues to hunt for HII. Post-merge: RC winner chooses Exile or Exile is odd person not picked for team. In Ep 11, auction item winner must pick exile.
Expired: F5 (presumedly, last played F6 and hidden F5, not found).
Ep4: Ozzy finds HII (only one looking).
Ep 10, Ozzy voted out with HII in pocket. Rehidden.
Ep 11: Jason finds it. Jason voted out with HII. Everyone knew he had it.
Rehidden.
Ep 12: Amanda found it (clue at EI, HII at camp). Amanda played it.
Rehidden at F5.
Ep 13/F5: Parvati sent to EI to block Erik or Natalie. Parvati doesn't bother to look for it.
Fake idol: Ozzy makes fake idol. Jason finds it. Eliza plays it, knowing it is fake.
Ozzy's alliance knew he had HII, including Parvati who flipped on him.
They knew Jason had gone to HII and found idol.
S17 GABON
1 HII at Exile Island, RC winner chooses Exile.
Twist: Choice between Tempation and Search for Idol.
Expired: F5
Sugar found it Ep 3. Held it until last time to use it (F5), gave it to Matty.
Fake idol: Bob makes elaborate fake idol, fools Randy. Randy plays it.
All 3 people to play a mistaken or fake HII were in fact eliminated.
S18 TOCANTINS
2 HII's, 1 at each camp. Clues at Exile Island.
1st Ep Twist: First Impression losers had a chance to find one time only HII at camp while others did trek.
Twist: RC winners choose 1 from opposing tribe; that Exile chooses 1 from winning tribe. Two urns to choose from, one with clue.
Expired: F5
HII #1: Brendan finds Timbira HII in Ep 3.
Ep 8: Brendan is blindsided with idol after revealing he has it and not playing it.
HII #2: Taj and Stephen find Jalapao HII in Ep 5, Stephen held on to it. Taj promised to share it with JT when he saw she had it.
Never played.
Fake HII: Taj and Stephen made a fake HII, found by Joe, not played.
Tocantins marked the end of Exile Island, after six seasons of it.
S19 SAMOA
2 idols, 1 in each camp.
Twist: RC winners choose 1 of their own to visit enemy camp, who gets clue. (Similar to China, but ambassador instead of kidnapping).
Post-merge: clues went to RC team winners. Russell found one without clue when he did not win RC.
Expired: F6 (Day 36).
HII #1 Foa Foa, Russell found Ep 2, supposedly without help.
Russell played it Ep 8.
Rehidden. Found by Russell Ep 9. Played by Russell Ep 9.
Rehidden. Found by Russell Ep 10. Never played. Worn around Russell's neck at F7 and F6 TC's.
HII #2 Galu: Erik found Ep 4, voted out blindsided with HII Ep 8 (merge).
Not rehidden.
S20 HEROES vs. VILLAINS
2 idols, one in each camp.
Twist: unannounced, hidden in Reward items.
Expired: F6.
HII #1-- Heroes
Ep 4: Tom finds it. Tom plays it.
Rehidden.
Ep 8: JT finds it, is caught and agrees to use it for tribe.
Ep 9: JT passes it to Russell.
Merge: Russell gives it to Parvati, who passes his and hers to Jerri and Sandra.
HII #2 -- Villains.
Ep 5: Russell finds it.
Ep 5: Russell gives it to Parvati at TC.
Rehidden.
Ep 9: Parvati and Danielle find it.
Merge: Parvati is not immune, but gives one to Jerri and one to Sandra.
Post merge (Ep 11 on): 1 idol.
Ep 11: Danielle grabs clue, Russell finds HII. Russell plays HII.
Rehidden. Sandra finds it Ep 12.
Ep 13: Sandra plays HII, last time to play it.
S21 NICARAGUA
2 idols, 1 in each camp.
Twist: Clues in Reward items are hard to decipher puzzles.
Expired: F6
Ep 2: Jill and Marty find Espada idol.
Ep 4: Na Onka and Brenda find La Flor idol.
Chase got Na Onka's HII when she quit at F9.
Sash got Marty's pre-merge, in return for agreement to vote out Jill.
Both played them at F6, last chance.
S22 REDEMPTION ISLAND
2 idols, 1 at each camp.
Twist: Clues in Rewards, successive clues.
Expired: Second F5, after RI returnee.
Ometepe Idol:
Ep 1: Kristina found it without any clue.
Ep 2: Kristina played idol. Rehidden.
Ep 4: Rob finds HII.
Rob keeps idol until second F5, then plays it.
Zapatera Idol:
Ep 2: Rooster found it without any clue.
Merge: Rooster plays it for Mike. Not rehidden.
Humor factor: Rob finds and (and with Grant) sabotages clues so that no one knows about them.
S23 SOUTH PACIFIC
2 idols, 1 in each camp.
Twist: Clues to HII are also hidden in camp.
Expired: Second F5
Savai'i idol:
Ep 2: Ozzy finds HII without clue.
Ozzy loans HII to Cochran to hold for him.
Merge: Ozzy's HII is wasted on Whitney.
Not rehidden.
Upolu idol:
Ep 5: Albert finds clue, shares it, Coach finds idol "for his F3 alliance."
Coach plays idol at 2nd F5.
Fake idol: Papa Bear tries this gambit as a bluff, fails, doesn't play it.
S24: ONE WORLD
2 idols, one in each camp.
Twist: No clues. Each HII earmarked for specific one tribe.
Manono HII:
Ep Sabrina finds it, gives it to Colton.
Ep 6: Colton med-evac'd right before merge with idol. Rehidden after merge.
Ep 7: Troyzan finds it. Ep 9: Troyzan plays it.
Salani HII:
Ep 5: Kim finds it after swap.
Only Kim and Chelsea know she has it as of Ep 9.
"If given a choice between two equally promising lines of play, always choose the more elegant." (a saying of my father's, later quoted by his bridge partner)