As was stated earlier, playing time is influenced by the material being recorded. If you search about for companies that offer mastering and pressing of vinyl, you will find that most set a limit of 23-25 minutes per side. This represents the limit of the room available on the disk. Another interesting read is about 'groove echo'.
One of the fascinating aspects of music recording, is the sequencing of tracks on an lp. A dance that artists, engineers, and record companies had to do.
The artist might want a certain track order, but this might not be technically possible, because of limits on recording time.
Also, tracks with heavy complex dynamics were to be avoided as last tracks on a side, because the closer to the lead out groove, the lower the effective speed of the cutter head on the vinyl or laquer, reducing it's capability to accurately record the information.
The record company would often want to be sure that the most promotable track always appear as track one, side one. The artist might feel otherwise, etc.
Sometimes, cassette versions of lp's had a slightly different track order, so as not to have the sides be of (too largely) unequal playing times. If side 2 of an lp was 23 minutes, and side 1 was 19 minutes, the listener of the cassette would have to listen to 4 minutes of silence, before flipping it over.
Going back to 8 tracks-they had the sequence all over the place, as there 4 'sides' to deal with.
Interesting now, with the fact that CD's are the predominant physical recording medium, with their 80 minute capacity, artists and record companies became free to go beyond the 45-50 minute limit that lp's imposed. The result is that vinyl versions of many newer recordings, are forced to be 2 vinyl disk sets, in order to include all tracks.