it's a myth that stems need to snap. some strains do, some don't.
you definitely don't want to overdry, but underdrying then redrying is not much better. it takes time to get the hang of drying and curing.
like kermit said, you want to jar the buds when they still have some moisture left in them, but not too much. they will redistribute the remaining moisture within the bud to the crispier outer parts of the bud when jarred.
sometimes, they get a little too wet again and you have to take them out to dry some more. that's jarring while too wet.
other times, you open the jar the next day and they are still bone dry. that's jarring after they are too dry. not as easy to come back from that.
when you do it right, you will open the jar the next day and the buds will be gooey again, but not wet. then you just leave the lid off the jar for a while until the outer parts dry again. repeat in shorter intervals until the buds redistribute all that inner moisture evenly. might take a week or so.
if you're unsure, just jar up a few buds and leave the rest hanging for now. a day in the jar will tell you what you need to know.