In reply to Jackwd:
Duncs did 50 for his 50th, and was finished by lunchtime, so it is very doable. He soloed most of them, and counted downclimbs as well as going upwards. He did it at Stanage, in August, rather than on his birthday in January! He had a little support team - one person to record the climbs, one to move the bouldering mat, one to take photos, one to lounge around looking good etc.... it was a great day!