As it relates to joining bicycle tube junctions, all the exercise in building towers of brass blobs tells you is, that there is a need for heat control. Otherwise you wasted a bunch of filler, and gas. Pretty hard to take your "heat control" exercise in building towers and move over to fillet joints on thin wall tubes. If you want to build "blobby" sculptures, great. If you want to build bike frames, get the real stuff and burn a few up. Honestly, if welding doesn't come natural to you get some instruction to go along with your practice. I know you have, but again take a look at the work by Steve Garro, Dave Kirk, and others. They didn't learn to lay fillets like this by building towers.