I have been on a fair few forum rides and have experienced both end of the scales. I kidded myself a few years ago that I was fit and went and did one of TF's fixed
Rutland rides. Never have I been so embarassed at my shocking level of fitness and fair play to TF who kept with me all the way, changed the route midpoint to cut out a fair few hills and even was helping pushing me towards the end. Not once did he moan and stuck with me.
I vowed to that day that never again would I be so under prepared and it is why I always try and head to Rutland to support his rides in thanks to the support he (and Dr_Pink) showed me on that day.
As long as the mileage, time, start and end point are mentioned then these things can always be tweaked and is they way they work best