it would depend on how many sources of healing there are, how much they heal, vs how much damage you can take vs what can be avoided.
If you are worried about people getting too many cookies early on you can make a loot table to where they are less likely to appear on lower levels, making them much more valuable to be saved. or to tackle people having too much, might i suggest you implement a "fullness" system that prevents players from spamming the cookies.
as far as waiting goes vs healing, i believe you said it was 10% and then it drops a stat if its higher then 5? dropping a stat is a huuuuuuge punishment for healing.
ive seen others that allow you to heal when waiting, its a very tiny amount per wait, but the flip side it leaves you "vulnerable" to enemy encounters per wait. so you'd heal 1-2% of your hp but run the risk of encountering an enemy. to prevent the risk of people spamming that you can have the encounter rate start off small, but then increase for each rest or something.
in the end, you do you, as the dev you wont make everyone happy so you should aim for just something that would make you happy.