There is an interesting twist to the issue if you are doing development support, having a customer ticket queue. If you are diligently fixing errors before they ship you can profit from that. The queue shrinks, the stress levels sink, management is happy with you.
However, if the number of tickets gets too low over some period of time, well, management gets ideas that you have free capacity. ;)
However, if the number of tickets gets too low over some period of time, well, management gets ideas that you have free capacity. ;)