I know a young geologist using his smartphone as a compass. When we were in the field doing structural measurements together, I would:
Record a waypoint using my hiking GPS
Take the measurement with my compass
Write it all down in my field notebook
Given the time to take all the things out, and put them away afterwards, it was at least 2$-$3 minutes per ...
Part of the answer lies in where the geologist will be working and if there will be coverage by cellular/mobile telephone networks.
It is my experience that a number of geologists, particularly exploration geologists, may work in remote regions where there is are no cellular/mobile telephone networks - parts of Africa, central Asia, Australia, South America, ...