Kidnapped and tickled. It may not be as prevalent anymore, to be honest, I haven't done story dives in a long time. But as someone that is an avid writer and RPer, it also immediately took me out the moment it was clear the story was just going to be another "kidnapped and tickled" story. Particularly when it's so...I don't know. Boring? They're not terrified or crying to anything someone would actually be doing if kidnapped. They just giggle and say "Come on stop" and shit. That's boring.
Also, and this seems to be a lot more specific to Japanese studios, but: I HATE a tickling scene that doesn't include fucking laughter. Laughter is one of the most IMPORTANT aspects of tickling in the first place, to me. The corner stone of showing when someone is completely broken and can't fight anymore. As a footfag, they could have the most beautiful gorgeous grippers across every fucking multiverse, but if all she can do is go "EEYAH" and groan/moan, it's an absolute waste.
As for "tickled for eternity", I'm actually a big fan. IF it is done right, which it only sometimes is. It seems like often just an easy phrase to throw in to say "ooo this is real torture, spooky and intenese" instead of what it should be. Tickled "for eternity" is not something where the victim says "Goodness please stop I'm quite ticklish on my feet" after having been thoroughly tormented for 10 years or whatever. I want to see the madness of it, mindless babbling of words they don't even hear anymore, long broken and rendered without identity that a wriggling mass of ticklish skin and endless laughter. Something like that.
But hey, that's just my 2 cents. Like what you like, no judgements.