Split grommet or frame?
For individual cables with a plug, a split grommet in a standard gland hole is enough. With more than six cables through one opening a frame is more economical: fewer holes to drill and a higher packing density.
Strain relief is mandatory
An entry seals, but does not hold the cable. Always place a strain relief comb or clamp within 100 mm behind the entry, otherwise a pull on the cable loads the terminals directly.
Plan spare capacity
Plan 20% blank grommets in the frame. A later expansion then costs a few euros for a grommet instead of re-machining a cabinet wall.