A nice feature would be to add a zoom percentage in preferences. Or 1 or more steps in between zoom in and zoom out.
While that request makes perfect sense and would also fix a long time pet peeve of mine, implementing it is challenging in Workflow’s current configuration tool because of the limited abilities of the 3rd party components we use for displaying the processes. So I’ll keep it in our TODO list, but don’t hold your breath for a short term solution.