More so during the pre-internet era than now.
Being a big prog fan back in the 70’s, prog albums tended to have cover art* that was a big clue as to the musical content of the of the recordings.
And this was especially helpful when so much world class prog started to be imported to the US from non-English speaking countries, and from more obscure bands.
Recognizing cover art that hinted at progressive music on the disc, helped me find some of the best prog on the planet, from bands that most people know nothing about.
*And no, I am not referring to the silly cliché notion that prog was loaded with themes of wizards, dragons, elves, etc.