Whenever I send a meeting request to my sales team, I monitor the response rate. The same 3 or 4 people respond almost immediately every time. The same 2 people usually ignore me, and the other 4 trickle in over the course of a few hours.
The quick response rate I attribute to Attention Deficit Trait, a new syndrome diagnosed by Dr. Edward Hallowell. At any one time, most of my team will be speaking on the phone, typing an email, surfing the web and carrying on at least one instant messenger conversation, so my email requests never come at a time when they are completely idle.
I agree with Hallowell's reasons about its ineffectiveness and why people find it addictive:
Full interview is here.
No one really multitasks. You just spend less time on any one thing. When it looks like you're multitasking--you're looking at one TV screen and another TV screen and you're talking on the telephone--your attention has to shift from one to the other. You're brain literally can't multitask. You can't pay attention to two things simultaneously. You're switching back and forth between the two. So you're paying less concerted attention to either one.
I think in general, why some people can do well at what they call multitasking is because the effort to do it is so stimulating. You get adrenaline pumping that helps focus your mind. What you're really doing is focusing better at brief spurts on each stimulus. So you don't get bored with either one.
After having slagged my team on this issue, I must come clean as being the worst starter of tasks that never get completed.