On Friday, December 18, 2020 at 11:11:02 PM UTC-6, wrote:
Anyway, despite a heck of a lot of long-grain surface to glue, I decided to use dowels to fasten the two pieces together. I figured that - if nothing else - they would make the alignment easy and nothing would slip when I put the clamps on. It worked well, but were the dowels a waste of time, at least for strength?

For me, its not a question of time. It's about stress. I get stressed if I am doing a glue-up that requires jostleing long or heavy pieces. Dowels or dominoes or (pick your own) greatly eliminate stress, especially if you need to use clamps to pull it together in alignment. You don't have to be concerned about the joint slipping around as you try to align it. I like doing things without stress. I'm not going to engage in an argument about strength.

Bob