What is the furthest you went on foot?

used to run marathons all the time in younger days (26 +/- miles)

10 miles in one day.

26.2 miles in 24 hours.

I walked the Pennine Way from Kirk Yetholm in Scotland to Edale in Derbyshire a few years ago that's 268 miles. Took 15 days to complete it, but I wasn't particularly rushing just enjoying the countryside. I probably actually walked 20 or 30 miles more than that because I often detoured to find less exposed places to put my tent up overnight or to replenish my food supplies in villages.

I did a sponsored 50 mile walk over two days

Wait? It took you 6 days to walk 27 miles?

I did a 24 trail mile day once on a solo backpacking trip. Sort of thought I was the shit. And then I read about Heather "Anish" Anderson AVERAGING 40 miles a day on her record setting, unsupported PCT trip.
Took all the "shit" right out of me.
That woman is a machine.

in one day? or a longer stretch
i have done 20 a day many times,
most of the Appalachian trail in big chunks.
a lot of the pacific crest,, big chunks