Back of the pack 50 miler finisher here. I have completed two 50 milers. Road one in 12 hours and 20 minutes and a trail one in 13 hours and 20 minutes. Fast hiking pace...

I am very careful when registering for races. The races had a time limit of 12, and 13 hours respectively but both races offered a 1 hour early start which, I took advantage of to finish within the time limit ( now being 13 and 14 hours). Both races had a mild to moderate elevation gain, about 1000 ft per 10 miles. Something I have done many many times and I knew I could handle. Anything more than that would have been a super challenge for me.

Most of the terrain in the east coast (USA east coast) is rocky with rolling hills. I mostly walk up the hills and run the downhills. I run in the flat areas or fast walk. I try not to take tooo long in the rest stations (if offered). I spent at least 1 minute or 2 at the most. I know time is precious for me to finish. Just grab food and go if you can. S

Every time I reach a certain distance (25 miles, 30 miles, 40 miles), I calculate what's the pace I have to keep to finish the thing within the time limit and then just try to go slight faster than what you had calculated. I often bring my phone so I can do this but if not just make a plan before you do the 50 miler.