Most tasks can be counter-intuitive when you multitask them, but sometimes you can easily do it with others. Having two screens does help me multitask and do more but I takes breaks and not always overdo things.
Working quickly can only help if you don't do it too quickly or mistakes are made and can be worse in the long run. It's all about finding that balance and what does and doesn't work and modifying as you go.
:) :)