I had to strip the caliper every 6 months, clean everything, lube and put it all back.
I started popping the calipers off and cleaning the pistons and sliders every 3 months without disassembly.
Did this for the last 2.5 year of ownership and daily use without the need to do a full strip down.
I would flush the fluid every year.
I've used the TRK seal kits and master cylinder kits on the GSX1400 and my Varadero and the seal have lasted longer than OEM ones and I haven't needed to rebuild the GSX brakes in the last 4 years, which used to be an annual thing with OEM.
Generally the early 1000cc and all 650cc bike (ABS or not) suffer from "shit brake syndrome"
The cure is to fit some 4 or 6 pots from iirc late 90's CBR600 or ZX6 with SV racing parts mounts, some have changed the master cylinder for a slightly bigger diameter piston one, but with mixed results.
The outgoing 650cc bike it top of my shopping list when the Varadero needs to be replaced and after the touring accessories I'd want, a front brake upgrade is next on the list!