I used to have an arm day when I first started this sport, simply because I felt the need for it. It sure allowed me to build a great base for arms.

I recommend supersetting biceps and triceps for a much less boring and overall rapid workout routine, especially if you want to workout each muscle group with 4 exercises (including forearms), otherwise you'll be looking at a really long workout session for arms only.

Strict rest time, form, concentrating on negatives and choice of exercises as well as their order will make the most significant difference in terms of results, at the end of the day.