The low end is often the toughest part to get right while mixing. This is especially true for people mixing in untreated or semi-treated home studios.
This was something I struggled with for a long time. I'd go to my car to do the "car check" and notice that depending on what the bass was playing, some parts would have an overwhelming amount of low end while other parts sounded thin and small.
That's where this tip comes into play. When I first learned this, I couldn't believe how much more consistent my low end was! No more random boomy notes and no more random thin notes. Just consistent low end!
If this is something you struggle with, this video is going to help a ton!