I find them frustrating as well. It always seems to time out or not load properly when I get to the checkout. I guess this could be blamed on poor service in places I shop, but because of this I rarely used the gift card option. I have been burned too many times.
I currently don't use gift cards (formally called Pay with Ibotta), but when I did, I would purchase my gift cards from home before I went shopping. I simply guessed how much I might spend. I also take a screenshot of the gift card just in case I don't have wifi or cell service in the store.
When I get to the store, I scan the gift card or have the cashier scan it. Anything I still owe, I can pay any other way. If there is anything still on the gift card, I use it next time.