Author here. Off the top of my head:

- Software is simpler than you think when you boil it down. There's a massive incentive to over-sell the complexity of the problem a solution is trying to solve, to pull in users. This is true both for proprietary products and, to a lesser degree, FOSS. You can probably replace most of the tools you use day-to-day in a weekend or two - provided you keep practising the art of just building stuff. I'm not saying that you should, but it's worth keeping in the back of your head if a tool is driving you mad.

- You can achieve 80% of the functionality with 20% of the work required to build an off-the-shelf solution. In a surprising number of cases, you can do the same with 20% of the integration cost of an off-the-shelf solution. A lot of software is - to put it quite bluntly - shit (I include a lot of my own libraries in this list!). There are probably only a few hundred really valuable reusable software components out there.

- Aggressively chase simplicity and avoid modularity if you want to actually achieve anything. The absolute best way to never get anything useful out of a project is to start off by splitting it into a dozen components/crates/repositories. You will waste 75% of your time babysitting the interfaces between the components rather than making the thing work.

- Delete code, often. If you look at the repo activity (https://git.jsbarretto.com/zesterer/zte/activity/code-freque...) you'll see that I'm deleting code almost as much as I'm adding it, especially now that I've got the core nailed down. This is not wasted effort: your first whack at solving a problem is usually filled with blunders so favour throwaway code that's small enough to keep in your head when the time comes to bin it and make it better.

- It is absolutely critical that you understand the fundamental mode of operation of the code you've already written if you want to maintain development velocity. As Peter Naur said, programming is theory-building and the most important aspect of a program is the ineffable model of it you hold in your head. Every other effort must be in deference to maintaining the mental model.