I picked up one of those "as shown on TV" records from the 70's, 'The Now Explosion.'

How did they get the groves so squished together? What is the limit that a LP can hold? This record had 10 songs per side.

It depends on how much dynamic range you want. The more compressed the sound, the closer the grooves can be. The old album "Super Session" has over 30 minutes of music per side (I just looked to be sure).

So - how many grooves are there on one side of a standard 20 minute long LP?:scratch2:

DH

It's not how many tunes per side but rather the total time involved. Extra time can be involved when the dynamics are compressed electronically so that there is little difference between the softest and loudest parts of the program material. This takes up less space on any side and allows more time and material on a disc. More time, less real quality and dynamics.

Kinda like the relationship between tape speed and quality.