If you ask me, it has to do with what size target you are slinging lead at.
For me, I focus heavily on being able to hold 3/4 inch or less for as many shots as possible, most recently I've finally got a handload that holds 3/4 inch for 10 shots. I stress being able to shoot to this level of precision or better so that I atleast know that I have the ability to hold the rifle steady enough that 400 yard shots on squirrels is not going to be a problem accuracy wise, it leaves me with only the elevation and wind adjustments to consider. It's hard enough worrying about compensating for trajectory and holding for wind, having to also worry about whether or not I'm holding the rifle steady enough to make the shot is something I'd am glad I don't really have to worry about. I also need that level of accuracy from my rifle/load combination for making hits at 400 yards, a squirrel when standing is right at 3-4 inches wide and that's within the accuracy of the 3/4inch rifle/load combination so if I'm ontop of my game I should be rewarded with a hit after factoring in the elevation and windage adjustments. If these were 400 yard coyotes a sub-MOA rifle certainly wouldn't matter, but a squirrel at 400 yards is right at or possibly even under the sub-MOA size range with respects to their width and the that could either be represented by them crawling on the ground or when they are standing. It gets hard, either you've got to be within 1MOA windage wise when they are standing or you have to be within 1MOA elevation wise when they are crawling if you want to make a hit.
Of all the skills I need to improve, atleast I've got out of the way the ability to hold a rifle steady and shoot with precision. I can shoot pretty precisely at just about any range once I've got a working zero for that range, the problem for me comes with spotting a target at an unknown range and making a first round hit. On squirrel sized targets I have a problem with this once the distance extends past 300 yards, 100-200 yards is a piece of cake and at 300 yards it becomes a little "iffy". 400-550 yards and it's mostly just take a SWAG on the elevation knob and if you're close use a quick "kentucky windage" holdover on it till the squirrel either gets in it's hole or until you make a hit.
I have gotten good enough on my dials that usually I can get within about 6 inches of a squirrel at distances of 400-550 yards and from there I use little changes in hold over till I make the hit. To date my best shot on a squirrel at long range was done within 3 shots at 400 yards and the time between the first shot and the 3rd shot was about 10 seconds. I have yet to nail a squirrel at the 450-550 yard line, I get close where I'm putting bullets under their bellies or kicking dirt in their faces but just haven't made a jackpot on one yet.
As for bigger targets? After shooting at squirrels for so long my confidence level of being able to quickly make a hit on a larger target has gone up significantly.
Most of my shooting is done with high power optics and from a prone position though.
With iron sights I can hit pretty well at 200-250 yards on plates as small as 8 inches square in size from a standing position. My skills with iron sights or shooting from various positions is being stressed and is improving with each action rifle match I shoot.