How do u know when u've done all of ur companions side quests? Does every companion have just one or?

I was just wondering if anyone has any experience of getting affection points in the end game? I'm a Sith Juggernaut and I'm currently using Vette (has abou 5500 affection points at this moment) 98% of the time. I was just wondering do you need to stick with just one companion to get their full affection and to get their side quests?