For a long time the English and Sicilian, now they are 2/4 of my main repertoire. I just took a long break from playing either of them, and then came back later trying new lines.
Also I"m assuming you have an opening that spurred you to ask this question, so what is it? 
I wanted to play the king's gambit, but never felt very comfortable with it. It's probably because I'm not very good at tactics that it doesn't work out very well.
For a long time the English and Sicilian, now they are 2/4 of my main repertoire. I just took a long break from playing either of them, and then came back later trying new lines.
Also I"m assuming you have an opening that spurred you to ask this question, so what is it?
the noteboom/trianle system, ive come back to it so many times because i really like it but almost ALL of my most embaressing losses have come from one of its lines.
Ill just suddenly out of no where get destroyed by players at like the 1300 level. Though most of them werent in the noteboom proper.
probably every opening i play, maybe it should be applied to chess in general
had an opening they really like, but suck at?
no matter how hard you try to adapt to it you just fail?