I know a strong grip is needed in all pulling exercises, so when is it a good idea to use straps?
This comes down to preference. Straps are not great if strength is your main goal because it is just extra help you are giving to your lifts so you do not get a true indicator of total strength. Straps will take away from your forearm and biceps strength, which is crucial on so many lifts. If you ever want to enter a raw lifting competition and you have done all your training with straps, you will be in for a surprise. You should train to mimic how you might compete, which is strapless. On the other hand, straps are fine for strict bodybuilding purposes, in that getting a few more reps on certain lifts can help you target muscles beyond failure, which is want you want. So again, it depends on your goals. If pure strength is your goal, then it is advisable to stay away from them. If you are looking to bring up bodyparts like your back, then occasional use is fine. Just do not become too reliant on straps.