Ways to improve my ab workout and other exercises

Hi everyone!
I have been going with this routine (noted down below) for almost a year now, and I'm happy with my gains so far. But I would like to have some tips on how I could improve my ab workout. Right now I do abs for about 8-10 min with weights on my crunches. But I'm thinking about working them out once per week instead, because I want to kepp my core strong.

Also I could not help but notice why Scooby changed this work out from 4 sets per exercise to 3. How much does that matter?
If their is something else that could be imporved with this routine, please make a comment about that.

As you can see its basicly Scooby's "Advanced Intermediate Workout Plan" with some changes.

Day 1
Crunches   4   8-30   
Bicycles   4   8-30   
Dumbbell press   4   6-12   
Dumbbell flys   4   6-12
Pushups   4   6-12   
Chair dips   4   6-12   (as many as I can)
Dumbbell french press   4   6-12

Day 2
Crunches   4   8-30   
Bicycles   4   8-30   
Overhand pullups   4   6-12 (as many as I can)
Dumbbell rows   4   6-12   
Underhand pullups    4   6-12   (as many as I can)
Dumbbell curls   4   6-12   
Hammer curls   4   6-12   

Day 3
Crunches   4   8-30   
Bicycles   4   8-30   
Squat        4       6-12 
Lunges   4   6-12 each leg   
Stiff legged dead lifts   4   6-12   
Calf raises   4   6-12   
Alternating dumbell press   3   6-12   
Side raise   4   6-12   
Reverse flys   4   6-12   

The 8-30 reps thing makes sense if you're working out abs three times a week, especially if you take into consideration the fact that all the other exercises, except for flyes and french presses, engage your core as well. The transition from 4 to 3 sets is not a significant one, as this routine setup will add very little mass to your abs anyway. If you're going to switch your abs to once a week (which I recommend) I suggest you do 3 or 4 sets of weighted crunches, doing between 5-12 reps (you can switch up week to week, doing 5-8 and 8-12 if you'd like) and follow each of the sets with either non-weighted bicycles, or bicycles with less weight. then you'd follow with planks or side-planks for as long as you can. I would do this all in a super-set, but you can also split this up into 3 exercises if you'd prefer it that way.

I personally don't work out abs, because the heavy compounds I do (deadlifts, squats and pull-ups) are enough to keep my core strong and fit; but if getting 6-pack abs is one of your training goals (common) I do recommend training them once a week (twice at most).

Gym?

single-leg get-ups and pistol squats.

I agree that 30 reps makes no sense what-so-ever for squats.