Definitely always keep an eye out for glowing plates.
In my experience, being off on the bias (even radically so) won't cause tubes to "lock" to that bias as you're afraid, El Barto. They are operating outside their normal range, tho, and this is hard on the tubes for sure.
I think you're quite right that a manufacturer wouldn't have bias pots on there that have such a range of adjustment that massive problems (like causing the tube to run away) could occur...
BUT, some food for thought: I was reading this morning about the new-ish BAT VK-55 and BAT included auto-biasing. They claim this is good to (obviously) offset sonic changes with tube wear, but ALSO to lessen wear during line voltage changes and (directly in reference to this discussion) to lessen tube wear upon start-up.
So there--I think you have a better procedure than I do