January 12th arms workout: When does a high volume workout become too much?

My enthusiasm got the better of me again, I was shocked to see that I had in fact done 19 sets for biceps today, and also 15 sets for triceps. At least two of the biceps exercises are primarily for the brachialis; something a man with my genetics would be well-advised to work hard to make your upper-arms look a whole lot bigger, but 9 sets for a small muscle is still way too much.
This workout was great fun mind, I certainly didn’t feel like I’d over done it, but when seen on paper it’s obvious I need to cut back on the volume. At least with my arms workouts I’m not going to be held back by any lack of weight.

Next time I’ll try the following: Biceps, close-grip bar curls, dumbbell preacher curls, standing dumbbell curls compounded with standing hammer curls, 3 sets of 10 reps each.
Triceps would be: 1-arm cable pushdowns, overhead db extensions, and either DB French press or my favourite, overhead cable triceps extensions. Again, 3 sets of 10 reps each.

Compare this to the current workout:

Cable pushdowns compound with cable extensions, 3 sets 10 reps
Close-grip bar curls 4 sets 10 reps
1-arm DB extensions 3 sets 15 reps
Standing DB curl compound with standing hammer curls 3 sets 10 reps
Reverse-grip cable pushdowns 3 sets 10 reps
3 tri-sets: prone incline curls, incline DB extensions, incline DB curls
DB preacher curls 3 sets 10 reps
Kneeling cable triceps extension 3 sets 10 reps
Reverse-grip bar curls 3 sets 10 reps.
Plus, DB wrist curls 3 sets 10 reps.
I’ve used a similarly high-volume approach since I started back with a vengeance in October, my arms had shrunk to 15 inches but were back to 17 inches by Christmas. This has also been my favoured approach for as long as I can remember, but on average I have tended to do between 9 and 12 sets per bodypart. My real high-volume workouts were with my Olympic lifting coach, often 20 sets +, but most of those sessions were about technique and motor skills.
Also by cutting back I could add some extra core stuff, or some kind of mini-circuit to address some lagging areas. I’ve been getting an average of just 6 hours sleep a night at the moment which is nowhere near enough, so I could easily be missing some clear signals about my recovery ability. However, as immense as the workout was, it was done at a moderate intensity i.e moderate weight, there no forced reps of heavy negatives to really burn me out either.