you tire quickly?? lower your bow poundage...you will shoot better.

just practicing wont make you better. perfect practice makes perfect. if you get tired, form gets sloppy and shooting suffers...then you form bad habits. bad habits are harder to break than it is to stick with good habits.

also, i find that shooting 3 arrows at a time, instead of 5 lets me shoot alot longer. heck...shooting 1 or 2 at a time i go real long. shooting for 4-5 hours just sounds crazy to me. well...ive done it...and suffered a close call with a shoulder injury...luckily i quit before it was an injury. shoot 20 or 30 shots a day. focus on good consistant form.

repeatability is what your looking for. good solid anchors, same sight picture and peep alignement, good loose grip, relaxed bow arm, good release.

also, try shrinking your target. i bought a pack of golf tees for like a buck or 2 at walmart. my bag is black and they are white. i shoot those even at 40yds. be surprised how much that can shrink groups alone.

time and practice will get you there...shooting lessons arent a bad idea. it'll jumpstart the learning curve and if you pay attention and keep doin what your taught, you will continue to shoot well. wish i woulda did that when i started...i pretty much taught myself and read what i could find online and on these forums.

good luck...lower the bow poundage and work on consistancy. consistancy starts with Y O U.