Long muscles have more strength potential I think.
As for progress, depends on your goals. For building up use the mirror to check progress. For strength its a different workout less reps more sets heavier weights. I have been doing this based loosely around a west side beginner routine, and get improvements every week. Last week I squatted 110kg, this week 127.5kg. Next week 140kg target. Only used weights 6 months and first ever squat was in April 07 with a massive 60kg.
My theory is to get big - eat big lift big.
You will not improve too quickly on the weight you can lift doing 10 reps to failure each week, but doing a day of heavy work not quite to failure (sets of 3 or 5 80-90% 1RM) and a day of speed work with 50-60% 1RM every 4-5 days (depending on recovery rate) will push a beginners lifts (I'm talking compound lifts) up to a respectable level quickly. From this base you can then do more reps if you want and you will build more muscle because of the weight you are able to train with.
This is my approach at the mo, I train 5 days a week and I have been building up to it. Its hard, and I will have to back off and detrain after a month or so, but then I can work up again. I want my squat to be 170kg and bench 120kg for Christmas. I seem to be going in the right direction. Read up on west side article here:
http://www.westside-barbell.com/Arti...0BEGINNERS.pdf