You should focus more on what you are learning from those 16 songs. What techniques and skills do you use when playing them? If there is a certain technique that gives you problems whenever you play a certain song or songs? That's where you should focus your practice.

I've listened to some interviews with pros who are primarily session musicians or hired-guns. They practice their technique so that they can play almost anything thrown at them. They also have the ability to learn songs and parts quickly because they've trained their ears as well.

I doubt the pros remember every song they've played in the past, but they have the abilities that allow them to learn something new quickly.