Alan,
It sure sounds like you have received a great deal of good advice in response to your initial post. I concur with essentially all of it, and I would add that I have given up many years ago on the goal of becoming an ASL 'rules expert'. The complexity and minutiae of ASL are a key attraction for me, and are probably the reasons why I have stayed with the game off and on over the years.
Note the phrase 'off and on'.
As has been oft mentioned, the best way to gain proficiency with the ASL rules and by extension, tactics is to play the game frequently, preferably with experienced players face to face if possible. In my experience, I have found that it can be both intellectually healthy and rewarding to take a break from ASL from time to time and partake in a sort of wargaming 'palate cleanser' by trying out some of the other military boardgames available. By this, I am referring to playing slightly less complex games once in a while.
Some examples would be the AH/MMP Great Campaigns of the American Civil War series or the (out of print, unfortunately) AH area-movement type games such as Thunder at Cassino or Turning Point: Stalingrad. Personally, I'm on a several months long ASL sabbatical and I'm enjoying a solo play of MMP's 'The Greatest Day', volume 1 which portrays the landings at Sword/Juno/Gold beaches and the subsequent breakout. Another great benefit of playing these games is that in nearly every instance, you will gain a more insightful historical knowledge of these battles by playing with a larger unit scale on maps which are far more historically representative than your typical ASL geo board.
How long should you take your ASL break? That's entirely your decision. I know that in my experience, the massive ASL rules set with its snap shots, street fighting, gun duels, concealment gaining and stripping, LOS, Chapter E, etc., etc., can become intellectually fatiguing with prolonged, continuous playing. Maybe you are at this point, especially with your work schedule as you described previously. This is in no way a suggestion to give up on improving your experience or proficiency with the ASL system. ASL is always there waiting for your enthusiastic return.
Anyways, these are just my humble suggestions, maybe they could work for you too. I wish you all the best, and by all means... have fun!