Silly to limit it to 24 hrs (or whatever). Not everyone comes here on a daily basis.
Not every control is a good one, nor necessary. Really, what is the harm in Thanking older posts? I don't see one, but I can see the advantage to it. In my own case, I enjoy being able to Thank posts who summarize a point succinctly so I don't need to repeat the same idea. Now, I have to quote that other person and, frankly, I can't be bothered most times. The OP actually loses out on that useful feedback (knowing several posters, esp. regulars, agree with a particular post).
Turn down the control rheostat, LA. Its not helping.
Second thoughts can generally be amended with judicious action; injudicious actions can seldom be recovered with second thoughts.
--Cyteen by C.J.Cherryh