I updated these plug-ins to include increments of 5 minutes.
updateEstimatedDuration.omnifocusjs.zip (88.3 KB)
I am not sure how to set the macro to just remove the duration but kind of interesting that you can just set it to 0 and it sticks.
(84.8 KB)
Thank you @kaitlin
For those using Keyboard Maestro here are some macros that make these shortcuts.
OmniFocus Macros.kmmacros.zip (18.8 KB)
