I shoot matches with (and carry) a Springfield XD.  When I dry fire I obviously have to rack the slide between shots.  I was wondering though if I used my Sig SA/DA for dry fire sessions, affording me multiple shots, would this be a good way to practice or would it cause training issues?  It seems like multiple shots with the heavy trigger pull would help but I don’t want to start if it could cause me some issues.

When I do practice draws and trigger control exercises with my Glock I reset the striker each time but when I do drills that have multiple shots I just press the trigger the same way I would as if it moved.  With the Glock you can put a piece of index card in front of the breech face so it won't quite go all the way into battery.  The trigger will move a bit then, not sure if the XD will work the same way.  Even when I shot a Beretta I didn't dry fire it double action each time.  I just pressed the dead trigger back the same distance and with the same force as if it was single action.

For da/sa, you can run the first shot in da, and then just not reset the trigger all the way to simulate SA for multiple shot strings.

Something i also do, is cock the hammer, and run my exercises while working the trigger to the wall at speed under stress, WITHOUT allowing the hammer to fall.  This allows you to know exactly just how much you need to have the shot break, so in match conditions you end up with better trigger control and reduce the amount of excess tension in your firing hand.  This is more effective with a lighter trigger than a heavier one (SA on my shadow 2 is 2lbs. 8 oz.) I learned this from my coach Sam Yu (part of Taran Tacticals team).

I do a combination of both of these throughout a session and it has had good results overall in dry and live fire.

You can dry fire a dead trigger. Its like dry fire for your dry fire.

The only real reason to reset the trigger is to notice the differences in movement of the front sight with changes to grip or finger position.

Dry fire isn't just snapping in. Dry fire is all of the practice that you do with an unloaded gun.