I have a wacom cintiq and as I work I use pen in one hand other hand on keyboard (short cut keys and such)…
mouse is at hand and swapped for somethings that it accomplishes better than pen…
I have a 3 monitor setup and the pen is mapped to the cintiq, so that anything on other 2 monitors I use mouse for…
there is however a way to switch from monitor to monitor and use the pen for everything…
part of it is decided by what you find comfortable as your way to work…
hope this helps