I have only been shooting traditional after years with compound for two years. I usually get in practice 4-5 times a week. I live in a neighborhood where shooting even 15 yards is not available. Fortunately I can drive to an archery range that is only ten minutes away. Still, for this reason I often spend too much time at the range and like you sometimes go until I get fatigued.
Several months ago I started viewing Rick Welch's DVDs over and over. Consequently my accuracy, and importantly, my consistency has jumped. Rick strongly discourages shooting groups and shooting for long periods. He says shooting when fatigued actually makes you a worse shot...creating bad body-memory habits. Now I still stop by the archery range after work, but I stay for shorter periods and focus on each shot. Doing so has also saved my shoulder, which was sore from too much daily wear.
It is anti-intuitive, but shooting less gets you more.
It is hard to stop sometimes though when you love shooting so much.
Scott