Originally Posted by GhostRider62

The thing is this, you have been doing endurance riding for a long time and have years or decades of experience. A rolling 100 mile charity event ridden fast for you might be 5 hours (or less) and since it could be fast from the start, openers the day before make sense to be able to access power and speed from the start. A 140 mile 10,000 elevation event for someone with fewer years and less preparation makes it more of an energy limited exercise. A better approach would be lower the glycogen stores on Wednesday and then try to fill them up (supercomp) on Thursday and Friday.

If I was doing a 20 mile Crit on Saturday, you better believe I would do some short quick efforts the night before. A 10-14 hour slog of a ride? Why? Most riders in these kinds of long events would be lucky to hold 70% of FTP and conservation of glycogen is an important factor in success.