How little is too little?
When you keep working with “low level” elements on a routine basis and you constantly feel like you don’;t want to be doing this. Abstract ’em away.
So when is it too much?
When you can’t make bits and pieces of some code parts on a regular basis and have to debug them down to the previous layer. You feel this particular layer does not contribute anything, just an obstacle. Drop it.
Where’s the sweet spot?
I like to apply the pragmatic approach. If you see a need for an abstraction and understand how it will improve your life, go for it. If you’ve heard there should be “officially” an extra layer of abstraction but you’re not clear why, don’t do it but research first. If somebody insists on abstracting something but cannot clearly explain what if will bring, tell them to go away.