My default xcut filing is the same 15/20. I have a 20" panel saw that I keep 25* fleam in as I use for finish cut and occasionally joinery cuts where the extra smoothness is appreciated. I also have an xcut I got from Mike Allen that has a slightly more aggressive than usual rake (like around 12 degrees) and the standard 20 fleam. Its very VERY nice to use on softer to medium hardwoods from poplar to walnut/cherry/soft maple. Both those though are still within the realm of pretty standard filing though, and for those with only one xcut saw I do find that 15/20 works best on the largest range of lumber species and thicknesses.
Woodworking is terrific for keeping in shape, but it's also a deadly serious killing system...