When you’re at a busy airport on ground, be patient after you issue a request. Most controllers will set a timer after issuing a command asking you to wait. Commands I use this on include hold position, line up and wait, exit runway and hold, hold short… you get the idea. The timers have a 1 minute resolution, so even though the reason you weren’t granted your request has passed, the controller may be off handling other situations requiring immediate responses, and when you’ve got a few timers running, it’s easy to get caught up handling the immediate requests. Rest assured, when the timer fires, and the controller returns to your frequency you’ll get handled. What’s a minute or two or three when you’re at the beginning of a long flight.
I use timers when I need to hold off as short as 10-15 seconds because in that time I may be able to take care of 3-4 other requests that don’t need to be delayed. Like I said, the minimum timer is 1min, so you may think “hey, it’s clear” and send another request. Instead, be patient. We will get back to you.