I totally agree with you annie.
Hard HARD limits is one thing and limits is a completely different matter.
My hard limits is scat, beastiality, kids and some more, but I dont find tickling a hard limit for myself but that just proves how different we all are doesnt it.
Being different is a good thing. and a good Dom and sub will learn from eachother where those limits are and which that can be pushed and which shouldnt be touched even.
Communication is of the upmost importance when moving into uncharted territories imo.

I like to push limits but moving into hard limits for myself or pushing my sub to places where she doesnt want to go is not something I want to do cause that could so easily be something that would break a trust that is hard to get in the first place and SOO much harder to regain.
and yes annie. Limits do change over time. My limits sure have changed and my likes aswell.

Trust
Communication
Sane
Safe
Consensual
those are just some of the important things to remember