Early levels you'll probably use 1 pet to kill a mob, then break charm and finish it off off... then charm a new one.
Later on, particularly after the cleric gets complete heal at 39... definitely worth keeping a pet, and even buffing it (haste etc) if you feel confident it's not going to rape you on a charm break.
Keep a bag full of torches on you at all times to help with dps when you're keeping pets
[You must be logged in to view images. Log in or Register.]
Sidenote: Don't drink too much fluid in a typical session, quick AFKs can be fatal later on
[You must be logged in to view images. Log in or Register.]