I would often do a bullet point summary/outline of my answer on the paper. That would have arrows and insertions and crossed-out stuff everywhere -- it was usually a mess.

But then I'd use that to write the actual text answer, and consequently, it was mostly clean. I'd still have to cross stuff out or add a phrase between the lines every so often, but once the basic structure was done, that was mostly unnecessary.

And if I was ever pressed for time, I'd usually get part marks for the outline anyway. Depending on the subject, I'd sometimes race through the questions doing just the outlines, and then come back to write the full text as a complete second pass.

To be fair, this wasn't creative writing. I think it'd be harder when the expression is the content.