Originally Posted by
3Cforme
No, you really can't. Further to answering your follow-on questions, there are routes (and times of day) where Diamonds and Plats are riding in the back. You can't assume that all Diamonds and Plats got upgraded at 5 days to leave you competing only with other Golds for upgrade space.
I believe that the poster was referring to looking at the Y-cabin premium seats prior to the 5-day window. If you see that all of the 'blue' seats are selected, then the flight has alot of medallions. I checked my MCI-LGA flight about 7 days out, and only one or two of those seats were selected (I cleared at the window as a PM on a 'T' fare). LGA-DTW was the opposite, and I missed the upgrade.