I put a huge focus on training the lower back - WHY? Because the lower back not only keeps the core section safe during training/sports/LIFE but a Strong Lower Back will dominate any workout. The back is prone to giving out on squats before the legs, deadlifts before the upper back, and poor training of the lower back triggers a lot of pain and injuries.
Too often, a lifter will hit 3-5 sets of deadlifts then spend the next hour hitting endless versions of Rows because big weights on a machine is cool and fun but very rarely do they focus on what is probably their actual weak spot (the lower back). I have also found that by training the lower back, athletes are able to quickly adjust themselves when their sport or lift puts them in an awkward position. Lifters with a weak lower back will get sloppy during training (especially if attempting a Max Out) but lifters with a strong and powerful lower back will keep tight and if by chance they do start to slip the body will naturally realign and just keep moving in the right direction.