(the bug bein' we don't have this feature, heh.)
was thinkin' a nice bit for landmines, vehicles that might fire multiple missiles, etc might be a "maxnum" argument, so you can set a number of items with a long expiry without worrying about delay. once the maxnum is reached, expiry +5 becomes the delay argument.
ie:
delay=50 (this value's in milliseconds or somethin, yeh?)
expiry=9000
this way i imagine you'd be able to lay down 5 mines, then you have to wait until one's blown up. once one's expired, you can lay another. if two expire, you can lay two, etc.