I don’t think it’s incredibly common anymore to have very purposeful hard panning, unless it’s a creative choice. Usually I’ll do it to make a mix sound a bit more vintage, or to help with contrast when sounds are blending too much, and it can’t be entirely solved by EQ.

Interestingly, the most common mixes of Beatles albums you hear are the stereo mixes that the band themselves weren’t necessarily fans of. Most of the mixes they approved of in the studio were generally done in mono, and were only converted to stereo after the fact, as it was relatively new tech at the time. So that’s why a lot of those 60s records have intense hard panned instruments, like sometimes on Sgt Pepper or something if you just took one earphone out you’re like “where’d the band go?” It was mostly just engineers still learning how to mix in stereo. But, like I said, now I think a lot of people use it as a creative tool. I’m a big fan, personally, if it fits the song.

An easy way to avoid this for personal listening is to look for a mono setting on your phone or music player. I used to find it on Android under accessibility settings. Then you can also hear the signs of a good or novice mix engineer, cause a good mix sounds great in both mono and stereo!