Totally understand! I run a lot of short tracks or smaller speedways so it’s not as noticeable just check for play in axle at home. Took a stab at a big 1/2 mile last summer 10th to 2nd around the top with no draft think I fell back to 7th though… went about finding speed the wrong way, worked for 2 laps lol
For sure. Any shifting or play in the axle could set you up for a wild ride

In addition to lock collars to hold things in place I also put a piece of electrical tape around the axle on both sides of the hubs, bearings, brake rotor and chain guard. If anything shifts the electrical tape will be crumpled on one side and have a gap on the other side.
The roll speed is really more of a concern for my two JR drivers racing on a 1/6 mile track since they don't have all that HP pushing them down the straights. Maximizing roll speed necessitates supreme maintenance of bearings, chains, basically all moving parts. Also, I've got two karts that stay looking brand new which I presume will help the resale value one day. I've got a buddy looking to start his kid in karting and my simple advice to him was don't buy anything that looks dirty no matter how good of a deal it seems to be.