You max out at 60 criminals every 5 hours. Let's assume you can get online at least twice a day, that's 120 x 18 = 2160 pies from criminals alone. Then add in your friend visits, which btw you really should be visiting ALL of your friends because you get 3 pies per town from tapping phones. So that's 3 x 100 for the phones = 300 pies. And lastly from tapping criminals in friend's towns you get, what, 270 a day? I must admit, I haven't paid much attention to that part since I know I'll be visiting all my friends anyway.
2160 + 300 + 270 = 2730
And that's only if you manage to visit twice a day. Since most of us are awake for more than 5 hours, you should be able to squeeze in at least 3 visits (once when you wake up, once at least 5 hours later, then once before going to bed). Which would bring your total up to 3810 pies a day. And that's not even counting the pies you get when your friends visit you.
Edit: I forgot about the HQ and Felons, which obviously add pies as well.
As of right now, I only have about 2 Felons at a time since I beat them so quickly. Once you get The Collector, you'll start defeating Felons faster. I generally only use Pieman and The Collector to fight Felons, and I keep Fallout Boy, Clownface, and Bartman on their 4 hour tasks to earn pies.