I learned free hand sharpening on a 1 x 4 x 3/8 pocket stone. Looking back, its a wonder I ever got anywhere. Moved to Arkansas stones until I got steels that it wouldn't handle. Then I moved to diamonds. Then a belt sander. After that I started with a Sharpmaker, and a cut block on a base to hold a coarse/fine bench stone at the angle I wanted. After doing that for a couple of years, I tried just using the stone with no holder and, to my surprise, I was better at it than before using the block. Now I use a beltsander, 220/1000 grit stone on a 17 or 12 degree block and the 40 or 30 degree slots on a Sharpmaker. I can still do it without the stone held at an angle, but not nearly as fast. Freehand sharpening is valuable if for no other reason than sooner or later you'll run into something that guides, blocks, clamps, etc. just won't fit.
I see a lot of pics with the stones or sandpaper sitting on a table. Why is this considered freehand? It's using the bench or table to hold the stone at a nice predictable angle. Stone in one hand, knife in the other is the only way to go.