Used to swear by taping every connector, figured it was cheap insurance. Had the same thing happen on a shorter run last month, tape snagged a nail and yanked the fitting loose, and I spent more time fixing it than I would have just pulling slow. Now I put a light coat of lube on the head and go gentle around corners, and I have not lost one since.

Does your brother in law actually test his joints or just assume glue is bad because it looks messy? I've had cardboard shelves with hot glue hold way more than I expected too, and if it works it works. Seems like he's just mad your builds take a fraction of the time.

Wait, six barrels off one downspout and he's only saving $40 a month? That seems like a ton of work and yard space for not much money back. I'd double check that savings claim before you start drilling holes in your gutters, because a couple barrels for your tomatoes is one thing but chaining six together sounds like a hobby more than a real money saver. Also, is the HOA really the problem here or is it the city rules? Those are two very different fights and I'd figure out which one you're actually up against before buying anything. If it's just about keeping some plants alive during a dry spell, fine, but don't expect it to pay for itself.