Electrical – have multiple GFCIs on one circuit

I have noticed that GFCIs seem to be worn out by heavy, prolonged loads. I can't find any authoritative sources for this effect. Probably the GFCI manufacturers know all about it.

The bridge circuit which detects the flow imbalance depends on some precision electronics which are heat sensitive. The heavy current itself does not affect them, but the side effect of that current heating up the components will lead to premature failure.

Answers in order:

1) If the kitchen was done properly in the 90's you definitely should have GFI protection, at least near the sink(s). If not then yes, you cetainly can install a GFI at the head of the circuit and protect downstream standard receptacles. Keep in mind, only receptacles serving countertop areas require GFI protection.

2) IF the house is that old GFI protection was likely not required at the time of original installation. You can if you like add it at any time, and it's the same situation as the kitchen. Downstream protection is fine.

3) See answer #2. I doubt there is a need for an actual GFI device behind the freezer.

4) Again, same goes. You can just use one GFI at the beginning. As for how many, there is no limit, but each downstream device does have a tiny bit of current leakage, so limiting them to 5-6 is a good idea.

Remember, to gain downstream protection, the incoming line must be on the LINE terminals, and the line to be protected must be on the LOAD terminals.