Well, yes, using the ignitors does wear them out, and they are a "consumable" item that cost a chunk of cash every time they are replaced, so using them when you didn't need to is a waste of money.
On the other hand, a big "bump" from turbulence can knock the fire out, so if you think there might be one coming, it's good practice to switch the ignitors on. By far the most wasteful error is to switch them on as you penetrate a bit of bumpiness, come out the other side saying "that was not so bad", and then FORGET to switch them off again. For an hour or two
