I use exclusively Nocturne. I build him as a bruiser and I jungle when we need one.

i have a main and a secondary and when i get bored of 1 i usualyl take up the secondary then get another secondary keeping it between 2 champions is a good way to go in my opinion

Yes.

For top, I main Teemo.
Mid, it's Annie or Ziggs.
ADC, Sivir or Ashe.
Support, Leona or Sona.

These are the champs I'm best with, hence I will mainly play with them.

Too many people hop around champs and never really learn any champs to their fullest potential. This causes bad players. That is just imo.

But on the other side of the coin;
1. You only need to worry about situational builds for one champion archetype
2. You can easily master one champion if you only use their mechanics
3. It's a fantastic way to get up to level 30, due to reasons 1 and 2


And also, it IS possible to have multiple main champions post-30. At that point, it's impossible to always get the lane/jungle every time that you want it, so you need at least one champion in each position that you're good with.