The thought of 'skipping' a muscle group workout is unheard of in my vocabulary but I understand why people do it because the focus is on other muscle groups. Some of you might skip arm days to build up other important areas like your back, legs and chest muscles. I agree that you should work on your weaknesses but do not forget to work your arms because they play a big role in how your other muscle groups develop....
Gun Show
Your arms are not just beach or T shirt muscles and performing endless bicep curls is certainly not going to get the girls. You've probably heard of captions like 'Curls for the girls' which is certainly not the case, stay focused people as your arm workouts are going to help you achieve a better body. When you train your arms you aren't just doing it for aesthetic purposes, this is actually a legit workout to help with other lifts you perform in your other workouts. For instance, good biceps will help with pull ups, deadlifts and better grip which can enable you to perform better in these exercises. Likewise with triceps, you can perfect your bench press, shoulder press and other movements that require the triceps to work as secondary muscle groups during heavy lifts.
Keep The Package
When you skip a workout for another muscle group you have to remember that you lose out on working the muscles you're skipping. It sounds obvious but you can take it for granted because before you know it, other areas have got to the point where you want them to be but the other areas are now lagging. My advice to you is to keep a well balanced physique by training all muscle groups and mixing up sessions when you have to work muscle groups to keep the complete package.
Improvise...
Sometimes there aren't enough hours in the day for you to train due to other things going on in your life, I get that! However, what I do recommend is you split up your workouts so that you fit in all muscles groups, there is no such thing as skipping sessions! Sometimes you have to be clever when you are training and slot in muscle groups with unorthodox muscle groups which you wouldn't usually train together. Legs and triceps, shoulders and biceps and so on rather than training arms on a designated day.
Arm Workout
The gun blaster workout... 10 reps X 4 sets
Olympic Barbell Bicep Curls SUPERSET with Hammer Curls
Reverse Barbell Curls SUPERSET with Narrow Grip Pull ups
Cable Bicep Curls SUPERSET with High Cable Bicep Curls
Dips SUPERSET with SkullCrushers
Tricep Pulldown SUPERSET with Reverse Pulldown
Close Grip Bench Press SUPERSET with Overhead Tricep Press
Summary
Remember this is a session to help build up areas which will help you your bigger and harder exercises in later sessions. The arms help with your upper body compound lifts such as deadlifts, rows, bench press and shoulder press to name but a few of the complex movements you will include in various sessions. Never skip an arm workout and let me know what you think of the workout listed within this post ;)