Even checking the darkside of the planet will take a dozen escorts (to ensure coms links, that he escort does not get wiped out before a message is sent - that sort of stuff), but a real planet is much more complecated. You have to check the moons, behind orbiting space stations, on the surface for PAD batteries, deep meson gun sensor arrays etc.
And all the while the locals will be attempting to stop your escorts (PADM fire, escorts, fighters, SDBs, orbital guard stats etc.)
You also need lots of escorts to stop all these misc troublemakers getting at your rear (troop transports, tankers, ammo carriers, carriers). They are also needed to escort your troop landers, and provide close air support even engaging airplanes, ground forces etc in the atmosphere. Battelships are not designed to do this. You don't need a spinal mount or a bay weapon to shoot down a fighter jet. Also just line of sight limits how much one ship can cover.
I think you need a set of escorts for independent missions - anti-piracy, flag showing, customs inspection, long term surveillance. and another set to escort the fleet and do the above.
The gazelle, fiery, Kinuir and the Sidaki class (from Megatraveller Journel) are examples of the first type, whilst those depicted in that Challenge Article ships of the black war, or within fighting ships of the shattered imperium are of the second type.
Cheers
Richard