GSSF can probably do that if they cut the number of matches and limit matches to just one day, but I for one would not appreciate it.
If a two-day match has 600 entries, that's 1,800 score sheets. With that many, there are bound to be a few errors. When pistols are at stake, no one wants any errors that might cost them a pistol.
Now there is staff time. Two per match, leaving on Thursday or Friday and not returning until Monday night or Tuesday. Many weekends have double matches. Every now and then they even get a day off.
Finally, there are now 100,000+ members to take care of.
Bottom line, GSSF does an amazing job, thanks to a very dedicated staff.