Relaxing dough — why does it occasionally tighten up?

Hi — I’m curious to know why there are times when I leave pizza dough in the fridge overnight that it seems very much not relaxed the next day.  (I don’t know the term for “not relaxed” — tight?  Rubber-bandy?)  In any case I thought that leaving doughs to rest for hours would relax the dough, and — perhaps incorrectly — I thought leaving the dough in the fridge would definitely relax it.  However, there are times when I take dough out the next day it is almost impossible to roll out and it springs back much like a rubber band.

To complicate answering my question, I tend to throw ingredients together for pizza dough without sticking to a recipe or method.  Sometimes I’ll use a starter, sometimes I’ll use bread flour, sometimes I’ll add oil, sometimes I knead a lot and other times not so much — so if it’s an ingredient or a method causing the rubber band dough I may be too inconsistent to narrow down an answer.  But — in a very general way — is there a combination or ratio of ingredients or a method that tends to create dough that doesn’t relax in the fridge?  

Thank you.