When you talk to clients that train at BE you'll hear some common words being used to describe the experience. Intense, challenging, tiring, fast paced. We like to get people moving and challenge them accordingly to their skill level. However, there is a point where too much hard work doesn't pay off. That's why on a clients off days from BE we develop a specific cardio program to ensure they do not over train, but still work hard enough to see results. It's a fine line!
Just like everything on this planet your training should be "seasonal" as well. You can't always go at an intense, crazy, challenging pace with your workouts. You will burn yourself out and erase or inhibit any progress you made.
Linked is a blog post from Chris Kresser. Chris has a very popular, well written and researched blog. This post dives into over training. It talks about how to recognize it and why exactly it's bad.