I used to know lots and used to make a point of learning them. But the more theory and musical ideas I consumed made me realise scales were bollocks and tend to lock you into certain things and phrases. I think a wider understanding of harmony, notes relating to current chord that you are on and where you are going with a hint of relation to the key or tonal centre, whilst knowing all the notes on the neck and intervals etc is what is important. Also your ear....f*** the rules.
When i used to hear Eddie Van Halen say the chromatic scale is the most important i used to think what a cop out, what's he talking about....he's right!