Well.... you have to have one for traveling in the car with; then another for the days you want a challenge; and then another when you just need to sit mindlessly at your machine; and then one when you want to appliqué by hand; and then one when you want to ..... etc.etc....
When I first started quilting I vowed I would only have one project at a time happening, but I've had alot of fun making/finishing etc. projects over the years & hope you continue to work on as many projects as you need to keep you enthused.