Saddle racks are important for saddle fit. What do the 4 saddle racks in the photo on the left all have in common?
They all will leave marks in your flocking. If your saddle is left on one of these racks for a long period of time without proper padding, the rack will leave dents in your flocking. Saddles sit on a rack for most of their life and one with side rails like these four, put pressure on your panels and overtime your flocking will form around the rack changing your saddle fit. If this is the type of saddle rack you have, make sure to use a few saddle pads under your saddle to reduce the pressure.
Personally, I use a sacrificial foam wither relief half pad under my saddle. I call it a sacrificial half pad because it now has such pronounced marks from the rack that I can never use it on a horse. I find that even covering one of these racks with pool noodles can still leave extra pressure that will unevenly compress flocking.
The second photo, on the right, shows the type of saddle racks I recommend if you are buying a new one. These stands support the saddle along the gullet and leave the panels free. They won’t impact your flocking or saddle fit.