I haven't much since the pandemic but I always used to carry a shoulder holster in jacket weather. That's the operative term. You
need a cover garment to use a shoulder holster for concealed carry and then you can't take it off in public. There are a surprising amount of opportunities for that in colder parts of the country but the situation has to be right. (No joke, I've done it with everything from blazers to cardigan sweaters.)
I only carried vertically in shoulder holsters. I could easily draw without sweeping any of my body
so long as I had a little space to move my left arm up as part of my draw. Honestly, that can end up being a consideration for any type of holster. Depending on what you are doing, how you are positioned, etc.; drawing from anywhere can involve sweeping some part of your body or pointing elsewhere. That's especially true when drawing from a seated position in a car, cubicle, etc,; drawing from cover, or drawing in a fight. While never pointing a gun at anything you don't want to destroy is one of the rules, there can be brief seconds in times of emergency where you don't have a choice. Keeping that finger out of the trigger guard until it's time to shoot becomes the primary rule.
Like
bigolegator
, shoulders holsters are the main time I carried spare magazines. Having a mag slot or pouch on the opposite side just worked. Already having a multi-tool and gun on my belt, adding anything else creates a Batman utility belt situation and just isn't comfortable for me. Coincidentally, I knew another guy who shoulder-carried and kept a Buck folder (for utility) on the opposite side instead of a spare mag.