Senior here! I'm doing the leetcode grind and in preparation of interview rounds at companies that ask those sort of coding questions: I don' think it's a waste of time, it so happens that those companies pay very well, if you're willing to run the gauntlet. Preparing for the interviews is a signal in itself, as someone who sat on the other side of the interview table, I know the hiring companies needs every last signal it can get.

I hope other seniors keep snootily refusing to do such interviews, for at least the next few months, that way, I'll face less competition :-)

You may not be aware, but anybody can start a company. It is not an achievement unless you call doing a bunch of paperwork an achievement.

Neither is having 25 years of experience. It is just a fact you have been working for 25 years, says nothing about how well you've been doing.