just so long as none of the cells have dropped below 1.5V, then there won't be any risk of shunts forming, more info here:
BU-702: How to Store Batteries ? Battery University

regardless of the current health, your packs will age all depending on the temp and voltage they were stored... lots of variables

Rule of thumb is the packs should be discarded after they lose 20% capacity. If you have a digital charger which displays how much current is charged into the pack then you can do the math.

For example 5000mAh - 20% = 4000mAh

After a few cycles... drain each pack to LVC, then check to see how much charge each pack is taking in. For general bashing around it should be no big deal to continue using your packs provided they are holding enough charge, but IR will be more important for optimal performance if you will be racing.

I don't have an IR meter either, but I can usually tell when performance starts to fade and typically replace most of my 2S packs around the 6 month mark... my 4S packs typically go a little longer, I just need them to last 12 minutes for a 10 min main + 2 min of practice.