A BIG mistkae I often see new lifters make is to train their favourite body parts like arms/chest every day.
As a general rule - you want to wait AT LEAST 48 hours between workouts to train a body part again.
Remember that when you are in the gym training, you are actually breaking the muscle down. It's when you rest that the muscle recovers and grows. Training arms everyday would be counter productive because you are breaking down the muscle constantly and not allowing the muscle to regrow and repair.
For guys with lagging arms, I recommend training triceps after chest, biceps after back and then adding in an additional arm day. Something like this
1. back/bi
2. shoulders/abs
3. rest
4. arms
5. legs
6. chest/triceps
7. rest