I think if you’re flying IFR then it’s probably better practice to file a plan for each leg of the journey, otherwise you would need to cancel IFR and ask the controller to keep your flight plan in the system for reactivation at a later time, which seems a bit cheeky. But I’m not a real pilot so take my comment as opinion and not fully informed 
Obviously for VFR you’re free to do as you wish, so you can enter a FP into the GPS and stop whenever.
I like to use LittleNavMap for my flight plans because I can create a long flight plan and then if I choose to stop, I can cancel IFR or redirect to land, then edit and export a new adjusted FS2020 IFR plan in just a few seconds.