Screw body part splits. You know, where Monday is chest day and you don't train those muscles or lifts again for another week. The missing variable in the typical bro-split is exercise frequency.
If you're like the typical lifter on a body part split, you change up your exercise selection, poundages, and rep ranges on a semi-regular basis, but you only hit every major body part once a week. In terms of intramuscular adaptations, strength, and hypertrophy, you'll plateau if you only hit every movement pattern once a week. The plateau-busting potential of increasing your frequency will shock you.
The Push-Pull Split
In order to increase exercise frequency, move to a push-pull split while reducing your overall daily training volume. Here's an example of what it'd look like:
Day One: Pulling Muscles
Day Two: Pushing Muscles
If you can train four to six days a week, you'll end up hitting every movement pattern two or three times every week. Think it's too much to recover from? It's not. The reduction in daily volume makes it manageable. On a push-pull split, with a nod to Lee Haney, you stimulate rather than annihilate. Not only can you recover well, but your strength will shoot through the roof by doubling or tripling the training stimulus.
Retire the body part split and increase your frequency. At the very least, give push-pull training a go for a couple of months and see what happens.