If there is no evidence of any grease escaping at a point in the shaft seals then it usually pumps the excessive grease directly back at the grease nipple. The grease has to travel around the circumference of the draw bar so I would apply a further application especially if it hasn't been done for a couple of years.
Pump plenty of grease into it. The old grease will fall in the road when hitch compresses when you are towing. It will come out of back underneath. Don't worry about the stuff coming out just give the nipples a few pumps with the grease gun twice a yr. thats what I do & it keeps hitch smooth.
Yes pump some more in. Any excess will just ooze out. Too little & the draw tube will rust causing hitch not to slide smoothly.. It's possible hitch geasing has been neglected. Even if caravan is serviced at garage once a yr it is still good for owner to grease at least a couple of times a year or more if caravan is well used.
Mine hadn't been done for a long time when I bought it as it had only done short journeys from storage to local site, it took far more than six, so many I lost count. Release the attached part of the rubber boot and you should see clean grease coming through if it was dry. When putting the boot back on make sure the drain holes are at the bottom.
When you've finished it might be a good idea to compress the hitch a few times by reversing with the car, maybe use a couple of wheel chocks to reverse against to help make sure the hitch compresses. In this way any excess grease that is forced out can be cleared up rather than be left to 'fall in the road' as Opensauce suggested.
Grease falling on the road is not a desireable situation for any motorist, least of all for motorcyclists and, on occasions, has been known to result in a dramatic reduction in life expectancy. Not good!
Yes I was waiting for somebody to pick up on that one. It is fairly obvious that grease in the road is not desirable but so are plenty of other things. Despite using the rather awkward method you suggest excess grease will still fall in the road so personally I would not bother.
You need a cartridge of multipurpose grease & a good old fashioned grease gun. Get all that from Halfords etc or buy online. Every caravanner should have that.