The goal of DOMS training is to make the muscles grow. We all have so many beliefs about training that we cannot discard any of them for fear we will be missing out on something. If you target arms for a month you don't have to train any other muscles in the upper body. You don't waste your time doing maintenance training because the other muscles in the upper body will be stimulated enough when you train arms. You have to give this a go and see for yourself. Bodybuilders do way too many exercises and do too many bodyparts each week. That is the main reason most stop growing.
Doing some exercises will not generate growth. That is disappointing. So you can use the DOMS effect to get feedback about which exercises are effective and which are not. Make sure you actually contract the target muscle and not cheat by recruiting other muscles to do the exercise. Again, if the target muscle isn't sore you didn't train it properly. In a very short time you will learn what to do. The main thing is you will discard what NOT to do. That is a big thing to learn re bodybuilding. It probably helps to have the muscle in a stretch position when you train it. Triceps and calves, especially, benefit from a stretched position.
There is no need to remain on a plateau. If you are not growing rapidly you are doing something wrong. You should eat enough to cause a weight gain. Those on a diet cannot expect to grow muscles rapidly.
Whether it is beneficial to feed the muscle before, during and after training is unknown but Milos and some others swear this is really helpful.