It's a bit of a struggle! Phoebe is aided by how long she's worked at the Crescent Moon, as well as the nature of the job - the hours aren't long except on weekends, and they're at night, so she does family stuff for a few hours during the day and then every few days takes some time to herself. She's much like anyone else who works at a bar!

During Phoebe's marriage (or pseudo-marriage), her time with Alec becomes less frequent, but she still typically sees him at the Crescent Moon and they sneak time together then.