That's true.

It still can be rather enlightening whilst producing/mixing/evaluating your own work.

Like checking if you have to much/any lows say below 80/100 hz
in the side channel. While i wouldn't advise eqing this out via M/S eqing @home- i would rather have a check what might be causing this.

In an article i read it is summed up as follows:

- No extremes (Low or high) on the side channel. The beefy lows and tops should rather sit in the MID channel.

- Significantly quieter side signal

- Ideally have the frequencies evenly go down like: \
from the low end to the top (say 10 KHz) in the SIDE channel