Fizzy, I usually hire an extra 1 or 2 extra ground handlers and maybe 1 extra customer service person. Mostly if I'm doing quick turn arounds, but sometimes even if I seem to have way more than enough time. It has alleviated alot of problems for me in the past for the most part. Just remember that after you do that, you click on your setting back to "automatically hire new people as needed". You also don't want to over hire either. Those 2 categories are the only extra ones I'll do on my own. Otherwise I leave it on automatic. I find for scheduling, as you mentioned, is actually a minimal lack of staff, especially if you are leaving plenty of turn around time. But thats my opinion and it works for me most of time in that case. Just a suggestion. It won't break your bank. Just go easy on the extra personnel.
P.S. Check your turnaround time for the aircraft you are using as well. It may say minimum 60 minutes, which in that case I'll add a little more time. Its a balancing act, I'll say that. I usually schedule 20 minutes more than the minimum time. If it says 45 minute minimum, I do 65 minutes. Your gut will help you too.