You can connect as many wires as there are terminals.
There's only one grounding terminal, so all grounds have to be pigtailed.
If you're using #14 wire, and your receptacles have 2 screws and 2 stabs per hot and neutral, then you can connect 4 hots and 4 netrals to the receptacle.
Since you can't stab #12 you're limited to 2 hots and 2 neutrals for a cheap receptacle.
If your receptacles have pressure plates which allow 2 conductors under each screw, you're probably back up to 4 hots and 4 neutrals on each receptacle