P1 / old tamagotchi - how often do they lose hearts?

(I apologize if this has been addressed already.. I tried my best to find the answer)

About how often do P1/P2 and other 90s Tamagotchi lose hearts after their baby stage? Is there data on this somewhere?

Supposing I don't want to let it drop lower than one empty heart, how often should I be checking it?

From what I recollect, a Tamagotchi in the baby stage should be checked at least every 5 minutes. Their hearts drop faster, but I don't think nearly as fast as an aging vintage Tamagotchi close to death (I once timed my aging Zatchi, and he lost three hearts in about 10 minutes). But if you are asking this because you want to get Mimitchi or other good care characters, then don't worry about the baby stage because it is not that influential on growth. I say this because I got a Mimitchi on my first run of my P2 but took slightly average care of it and didn't give it any special treatment during the baby stage. Also, the heart meters dropping down to two empty hearts on a few occasions wont destroy your chances of getting a higher care character, as the heart meter dropped to two hearts a few times and I still got Zatchi.

I don't know about the other vintage versions beyond the P2 (might as well group it in with the P1) and the Tamagotchi Angel. The Tamagotchi Angel is pretty carefree, as even with 15 care mistakes I still got the best care adult and then eventually the twin angles.