I never use a gallows tool for tying dries. I learned to tie them before I had purchased the gallows tool, so the tool seemed too much of a hassle after learning to tie them without it.
However, there is one particular style of fly that I do use the tool for. It's the dandelion style emerger dry/nymph. I'll use the tool for making the dry/parachute body, then tie the dry part of the fly onto the nymph part.
They are probably good tools for people who have never tied dries.....but if your already tying, and set in your ways (like myself), the tool may be more of a hassle than a help.
