My laser is also a Generic Chinese Red and Black, 80 watt with a 750 x 500 bed. I rarely cut anything larger than 450 x 300 purely for convenience. I purchased it as a hobby machine and that's all I currently do with it. I actually use the kerf (cutting thickness) to my advantage and make no adjustments to compensate. If I'm cutting a slot in 1.5mm ply for example, I'll make the depth 1.6mm so that the two parts will sit neatly. The glue takes up space, and the .1mm seems to be good enough. Gluing the remainder of the slot is fine because the kerf allows space for the glue.
I'm not a rivet counter, but I do have a good eye at age 79. If it looks good to me, it will probably look good to most people. I don't worry about the few who may wish to criticise. My machine isn't entirely accurate, but any imperfections add character to the job in my opinion.
I spend a lot of time on the plans making sure everything will fit. I'm sure you will have done the same on your projects. I keep the machine clean, but otherwise it worked out of the box. I mainly make buildings which don't suit this site, but I've also built an HO ship and Gantry which I'll post tomorrow if I get time.