Many people use more aggressive spreads
A lot of people use 1-4 spread on single deck, and 1-6 or 1-8 on double deck, for instance.
That wouldn't be confined to single-deck. Abdul Jalib M'Hall for instance, thought shoes were a waste of time without a humungous spread of 1-30 or more. Many people think this insane, but then Abdul probably has made more money than them!
I've violated the 2x rule myself, it is just a good principle to fall back on when unsure. It is much more important however, never to underbet 2x than never overbet. One of the main reasons new counters fail is inadequate spread.