Haha, well, I haven't exactly spent years on this. I'm actually sharing my experiences with you because I'm still a newbie unlike many people here
(who are more experienced than us but who are basically giving you the same advice I am giving you). Like you, I've practically just started, I'm still in the testing phase, and I also started with digital. I'm giving you my perspective as someone who has probably only developed about 10 batches of film at the most. It's just that the little experience I do have has gone a really long way for me.
As you know by now, most the sentiment on this forum will usually be about establishing a pretty consistent developing process/system. Of course many of us will run into availability issues, temperature issues, and many other issues that are largely out of our control. But, we can't expect everything to be in our favor, and some things just have to be accepted as imperfect. Yet, there are usually ways around most problems. If I sense an availability issue coming up, then I do my best to save up a bunch of money and purchase what I need in bulk (e.g., suddendly discontinued film). It's very much about anticipation, preemption, and staying ahead of the ball. To keep my water bath from overheating (past 20C/68F), I keep ice cubes nearby that I can drop in and keep the temperature cool and consistent. If it cools down too much, then I can add warm water to bring the temperature back up. Some people might not prefer that way of doing things, but it works quite well for me.
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As far as developing is concerned, I honestly wouldn't worry so much about the out-of-focus issue. It's just an external issue. If your images are out of focus, then it's probably not because you're not developing them correctly. Once you get to the point where your shadows, your highlights, and your midtones are right where you want them to be, you'll feel more confident about developing. Developing is more about exposure and contrast so that's what I'd pay more attention to.
Like you, I've ran into a lot of external (but frustrating) issues ever since I started developing. For starters: A) I learned that my camera naturally jams every so often, B) I discovered that there was a piece of tape that had got stuck in the window of one of my film backs
which showed up in several rolls of film before I finally discovered it, C) I learned that a part of the shutter in one of my cameras was broken, and D) I just learned that a piece of wiring on one of my steel reels is scratching frame #3 on my negatives, and so on and so on. That doesn't even include the list of mistakes I've made while practicing the development process itself. I doubt very many people have had a perfect time with this, even the most successful photographers.
It was just last week when I was sitting there debating whether or not I had the sanity to continue developing my own film. Eventually, I decided that A) I still had a lot to learn and that I was just going to have to suck it up and put in the work to iron out all of the bugs, B) I can be very happy that I have already learned a whole lot with very little experience in this short period of time (in spite of my frustration), and C) once all of the bugs get ironed out, then the end result will probably be well worth all of this effort.