I still need to do a lot more tests with Griot's Ceramic 3-in-1 Wax including toppers. I have a door on the test car approaching 8 months of durability protected with two coats of Ceramic 3-in-1 Wax that is still trucking along without toppers, just routine washes. Really strong performance up to about 4 months before it began to start dropping off slightly towards the top section of the door, but some strong performance still remains beneath it the last time I washed it at 7 months.
I would be tempted to use something lighter on top of it for maintenance, like Speed Shine or Best of Show Detailer. At least on this car, it's proven it can hold up very strong with two coats for me, so I would start off with something light like Speed Shine just to keep up on the slickness and clean up some water spotting and then go with another coat of Ceramic 3-in-1 after 3 months and cycle that combo until the next polishing session.