How often do you need to replace straws and gaskets?

Reviewers in r/moderatelygranolamoms and r/Mommit consistently flag straw replacement as the main long-term cost. Thermos Funtainer is repeatedly praised for having all silicone parts fully removable and replaceable, while Simple Modern reviewers note straws can fall out and need swapping. Plan on replacing straws every 3–6 months with daily use.