With pasta you can grab a bit and just taste it. If its still solid on the inside, its not done yet.

/Just over the hill many Italian people flail their arms wildly after hearing this.

Pasta should have just a little bite, just a little hardness on the inside, to be the perfect al dente. And if you’re cooking it again (eg a pasta bake) then you should boil it even less or not at all (I don’t know of anyone who boils lasagne sheets).

But at the end of the day most of what you do with food won’t ruin it completely, and much of it comes down to personal preference. The secret is to taste everything (except raw meat, of course) - if you’re adding something, taste or smell the dish then taste/smell the thing you’re adding to help guess how much you should add, then taste again after adding and stirring. If you cook food to your own taste then you’ll pretty much always enjoy it.