there's a couple thousand things floating around in their mind. Language structure, personal & system API's, style rules (you asm guys probably don't see to much of this... :-), variable scope and values, etc... Humans don't have a stack. Interruptions cost me dearly. I can do test execution in a high interrupt environment, but not test development.
I worked once at a very "enlightened" company and we attepted to measure the cost of an interruption. This was not our forte so, this can not be claimed as 'scientific'. We came to the cost in time of any interruption during coding would average 22 minutes. As a result of this, the operator were instructed to say "in meting" to all callers except during tow hours of the day (one in the morning - one in the afternoon). Calling out, of course was unrestricted.

So I understand Richard's premise about phone calls, but I could never submit to his micro management. It's a form of management laziness, and poor substitute for measurement of progress and results. But hey... Some people think yelling has a place in business too.

If you work with 'real' people only one form of management should exist: "tell me whan you can have it ready and have it by then" and that should not be under threat of dismissal as Richard suggest, but, to quote a manager I once had "I can handle change, but only if you tell me before it is too late"

Erik