Is this thread still funny? Was it ever? It seems more than a little like taking candy from a baby. It's obviously not difficult to find LPs with sides longer than 20 minutes. There is none the less a technical limit with album sides that has affected artists in the past. For example, Jack Bruce's album, Things We Like, the original LP was organised as follows:
All compositions by Jack Bruce, unless otherwise noted.
Side one
1. "Over the Cliff" – 2:56
2. "Statues" – 7:35
3. "Sam Enchanted Dick" – 7:28
a. "Sam Sack" (Milt Jackson)
b. "Rill's Thrills" (Dick Heckstall-Smith)
4. "Born to be Blue" (Mel Tormé, Robert Wells) – 4:26
Side two
5. "HCKHH Blues" – 8:59
6. "Ballad for Arthur" – 7:42
7. "Things We Like" – 3:38
Side one is 22:25 and side two is 20:19, so both are over 20 minutes, but the originally planned track 8, "Ageing Jack Bruce, Three, From Scotland, England" (Heckstall-Smith) – 5:20, was omitted for technical reasons. This would have made side two longer than 25 minutes. This track, by the way, was later included as a bonus track on the 2003 CD reissue on Polydor.
There are real physical limitations on sound quality for LPs that prevent cramming too much in, so, to make this more challenging, start looking for LPs with album sides over 25 minutes, I am aware that there are some out there.
Any goose with five minutes to spare can find an LP with at least one album side over 20 minutes.
An interesting web page about LP mastering can be found
here. This article indicates you can have an album side over 40 minutes, but the sound quality will not be good and a more realistic limit is around 20 to 25 minutes depending on various important factors.
PS: The above album is interesting to me because John McLaughlin was the guitarist. This is before the existence of Mahavishnu Orchestra.