[whiskykilo]

Between 20-30% would be my best guess. I'm including business emergencies as well, regarding client support. These emergencies get me out of the groove, which also adds up wasted time, while I try to get back into what I was working on.

[beat]

Thanks for the reply. I'm working on a product that directly addresses the time lost to emergency failures in complex system, so I'm hoping to find a way to get a decent measurement of how the engineers doing the work perceive the loss.

If I can put it in reasonably defensible numeric terms for the managers/directors who can purchase software ("I can save 5% of the time of your senior/lead engineers!"), it'll be much easier to sell.