The best advice I could give you on reducing packing time is to know what you need and know how to pack it.
Besides the main categories (bag, pad, tent, clothes, food, water, cooking gear, rain gear, etc.), you also have the miscellaneous gear which is what I was always afraid of forgetting (thus I used to take forever when packing also). I have put a lot of thought into paring down my miscellaneous gear so it fits in a small ditty bag, which is where it always stays now. As long as I remember to bring it, I never find myself on the trail realizing I've forgotten some small essential item. For illustration, I'll list the items below.
Toothbrush/toothpaste, various fire starters (in plastic bag), spare compass, headlamp (plus a spare micro LED), first aid kit (bandaids, sterile/antibacterial wipes, nail clippers, tweezers), pencil and some paper, extra guy line (with mini carabiner at one end), water treatment, toilet paper and a small chamois towel