I can do 60s in bursts, and the bursts have lasted as long as 2 months before. I usually burn out as soon as we hit the finish line, and work 10-20 hour weeks for a while until all the comp-time is used up. But I can really do a fantastic amount of programming when I dedicate my entire brain to the project and completely exclude all other thoughts. OTOH I have to admit that both of the biggest production screwups I ever made happened in those crunch times. But seeing myself hit those levels of productivity actually gives me a ton of satisfaction. Some of my normal 40 hour weeks when my head isn’t in the game are so un-productive that it depresses me.

You asked about objective measures, but I’m not sure how programming can really be quantified. All I can say is my “hyper-mode” has caused projects to reach deadlines that others on the team thought were unlikely.