It's probably not all of them, lots of people use them with no ill effects but I personally had a problem with one at the beginning of last year and I have no doubt it was the bulb. I've since heard they should be mounted horizontal, I had mine mounted vertical in a dome. I don't know if this was the reason or not but I won't use one again.
https://tortoiseforum.org/threads/coil-bulbs.166917/
I don't think your opening a can of worms though. That's what this forum is good for, discussions on tortoise husbandry, and different opinions.
Why take a chance?