A tickle fight where the person who gets the other to say "i give up" gets to tie them down and tickle them for five more minutes at the end of the video.
On multiple occasions, where we didn't take the time to undress.
It didn't affect her ticklishness, but it was easier if we decided to do a five to ten minute session before dinner.
A machine could tickle someone continuously for much longer than a human, (we are taking into consideration that the ticklee is tied down and utterly defenseless) before needing a brake (you could just leave it on over night (to the true nightmare of the ticklee)), and it could probably tickle...