If TT bearings are removed, thoroughly cleaned and flushed and repacked with a very good grease like CHEVRON'S Red Grease, or LUBRICATION ENGIN'EER'S Almagard 3752, a properly performed repacking should last ten years minimum. A friend has an automobile transport trailer that is rented out constantly. It has surge brakes. He repacked the bearings in the year 1988. Five brake jobs without turning the drums. Good grease is entirely a different animal than run of the mill grease. I lubed a Willys Jeep pickup with this grease in 1974, and submerged the vehicle so many times in fresh water, it could have grown gills. In 1982 I tried to lube the zillion fittings and the least amount of Almagard pumped into a zerk fitting forced an equal amount of the red grease out. The stuff is amazing. Chevron came out with it's Red Grease 18 years ago and it has the same properties. The lubricity is so good, seals do not wear out. I lubed a friend's boat trailer bearings back in 1974. He passed away and in 1995 the new owner inspected the bearings, called my friend's wife and asked "These bearings were recently repacked by whom?"
The "issue" of bearing repacking should not be an issue at all IMHO