Every year, usually in Spring and fall, but since I run A/TW more about when i have wheels off than anything, the calliper slide pins are taken out, cleaned up on a wire whee and greased with silicone lubricant. I usually pack some extra into the rubber dust shields to make sure they are positively pressurized with grease, and then put it back together. Usually the lower bolt on the front callipers has some rust at the bell end. The last year or so I noticed the calliper slide pins were getting putted, and the rubber at the end furthest into the calliper bracket was getting deformed. I looked to buy some replacement pins and rubbers in Canada, but the cost was close to $100 even at a trusted parts store. They only came with the pad spring clips and those were not needed. I bought the parts, and then took them back realizing that eventually I would probably swap out the callipers, and the price was not much more expensive and included all hardware. Enter Rock Auto and I was able to buy new pins and rubbers for all four corners for about $25 delivered to my door. Will be putting these on and servicing the brakes soon.
Will post a few more photos of the swap and install to show condition of older pins and rubbers.