Theoretically a longer sight plan*could* make it easier to be more accurate but only if the shooter is able to take full advantage of a sight bar that is shorter.

A sight bar can be used for several things. First of all, you can use it to help adjust balance of the bow. You can use it to make the pin guard/scope housing fit the peep sight perfectly. You can use it to adjust so that both the pin and target are clear. If someone has a weird anchor point and peep height you can adjust the sight bar to help get the distance you need out of a bows site. For example, in FITA archery mens classes shoot out to 90 meters. For people that have a nock to peep height of any less than 5" or so it is very difficult to get the arrows fletching to clear the scope housing because of how low the sight has to be adjusted to compensate for this distance. If you bring the sight bar extension in closer to the bow it will move the bows group up to help one get this distance. This is an extreme example but the idea holds true even for hunting sights when people may have a weird anchor point........shorten the sight extension and the group moves up. You can use this if you run out of elevation adjustment on a sight.

One would think a longer sight plane would make you more accurate but I have seen many people at the top level nationaly shooting 90m groups the size of a softball with a sight extension less than 6" in length.