You can draw at any time and anywhere. All you need is a pencil and a ground to draw on. And if you really want to become an artist, you should always be drawing inbetween. All the great artists I know have done that.
Much drawing gives you the security of shaping out any form in your paintings!
A basic course of 3 or 4 days in drawing is also very useful for any painter. Even that you are not going to be an expert, the simple knowledge about proportions, perspective and the light and shadow in a picture gives you a lot of self-confidence, when you trace out simple forms in paintings.
For beginners, a DINA 4 drawing pad and a pencil B 2 is best. The advanced user will try charcoal or drawing ink.