Yep, "skip the prep work and things fall apart" is exactly right. I had a similar issue with a project where I was welding some heavy brackets and kept getting cold laps no matter what I did. Finally figured out I was moving too fast and not letting the puddle wet out properly. Slowed way down and focused on the basics of torch angle and travel speed, and it cleaned right up. It's almost always the simple stuff you know you should be doing that saves the day.
Yeah, skipping the prep work is so true... My cousin rushed painting his room without taping the edges first. Had streaks all over the trim and had to redo it, which totally echoes what @piperg10 said about things falling apart. Spent more time cleaning up the mess than if he'd just set up properly.