It really comes across that you are rushing, and that just isn't related to power tools. I'm noticing a lack of research and a lack of care.
Bring it back to my primer comment two posts up. I pointed out how removing 3 screws could have prevented you from getting primer on speaker grills. Your response was more or less that you wanted to paint them anyway. That is fine if you wanted to paint them, but you just slapped some primer on installed grills. Aside from the fact that the primer isn't for plastics, that primer is meant to be thick to cover wood stains that normally can be seen through paint. That thick layer is only partially on those speaker grills, meaning when you paint it black, the edges where the primer stops will be visible through and you will have lines on your speaker grills now.
Second, you have primer filling the edges where the speaker grill meets the wood. That will always now look goopy instead of sharp and crisp. Your screws will be partially filled with paint and if you ever do need to remove the speaker grill, the black layer will likely scrape off, showing only white primer.
What you should have done is taken the speaker grills off, painted them separately if you felt it necessary, and then put them back on after all painting is complete.
This isn't an isolated item. I am noticing a lot of areas where a little extra care would have made a world of difference, like your patch job on the miscut speaker hole. You put your patch wood there, that is fine, but then you cake on some sort of thick putty, sand off extra and paint the wood. What you should have done is repeated the process until you came away with a smooth product. If you weren't getting the gaps filled like you want, then use a thinner putty, or get something like Durhams water putty where you can control the thickness. Dill, sand, repeat, repeat, repeat until you are feel the surface is glass smooth. Only then should you put your first coat of paint over your job. (While you are at it, you could sand the entire board to remove the wood grain).
Just looking to help, bruv. There is a solution to every problem, you just have to set a bar for yourself and plan to constantly hit above that level before moving on.