I assume you mean formulations (especially post titles) like "rational home buying", "rational childcare" or "rational dating".

While I do not like those formulations, I like formulations that replace "rational" with "optimal" even less. To me the word "optimal" is mostly a mathematical term (Wikipedia redirects optimal to mathematical optimization) and does not acknowledge that humans have complex values, limited knowledge and resources and that there are costs in those activities. Also I understand "optimal" to mean maximally good. If something could be better, it's not yet optimal. That means something like optimal childcare might require super human capabilities.

Formulations like "rational home buying" sound silly and even cultish, because "rational" is completely redundant here (it makes you wonder why they won't shut up about their favorite subject "rationality"). "Rational home buying" is just about home buying. No one is is deliberately irrational. I'd suggest to just say "home buying", unless you really want to contrast it with irrational home buying.