I haven't been as dedicated to dry fire practice recently as I would like. Gone are the days when I was getting in 30-60 minutes daily, rather it's closer to 10 - 20 minutes once or twice a week. But even at that rate, there is benefit.
One lesson I remind myself of constantly in dry fire is grip pressure. It's easy to get sloppy with the grip on the firearm when the gun isn't actually firing. I had to break a weaker grip habit a few years ago after many months of poor habits in dry fire practice. If my hands don't show signs of the grip texturing after practice, I know I was sloppy with the grip.
Dry fire practice is a bit different with the striker fired SIG P320 than it was with the double/single action P226. Rather than every trigger pull being a full DA pull, the P320 practice is a lighter "dummy" pull. Despite the dead trigger, it's more realistic.
Practicing reloads is a changed experience as well. The P226 slide would go forward from slide lock when the magazine was slammed into place. In addition to that being less reliable than slingshotting the slide, I got "trained" to not do it. That caused issues when the slide didn't go forward on its own. I never spent significant time just practicing slide lock reloads until switching to the new gun.
To work on the reloads, I fill a magazine or two with inert dummy rounds and place them on the belt. The gun has an empty magazine and the slide locked back. Starting with the gun positioned like I just fired the last round, I drop the magazine, retrieve the "loaded" magazine from the belt and complete the reload — remembering to rack the slide. Then the loaded mag goes back on the belt, an empty mag is inserted into the gun. Racking out the dummy round locks the slide back, and the process is repeated. Again, and again.
Under the 2017 IDPA rules, reloads with retention, as well as reloads on the move come into play more frequently. I combine reloads with retention, or tactical reloads, with movement drills. My concentration when moving is on my feet and only pulling the trigger at the most stable part of the step. In my basement dry fire area, the floor is covered with various rugs. This provides enough surface variation to balance keeping the feet on the ground as much as possible, while lifting them enough to prevent tripping.
During each practice session, it's important to always use a timer for the start beep when practicing drawing the gun. I also work on table starts, with both a "loaded" and unloaded gun. There are multiple targets, and even a barricade set up in the basement, so just about every draw of the gun is combined with "shooting" multiple targets and some movement.
Twenty minutes is about the maximum time for effective dry fire practice, for me at least. That time encompasses dozens of gun draw and magazine changes. Interestingly, looking through my notes, hardly a session goes by that I don't recognize some improved technique or point for awareness. Now I only need to get to it more frequently.