It actually did make a difference many years ago when oxygen tight (butyl) rubber was not available for tubes and tubeless liners. Then you really did pump up your tires every few days until the oxygen was replaced by nitrogen (and a few other large trace gases). These days the main cause is damage to the tubeless liner, or leaks in valves and wheels. The leaks in valves can be overcome by using caps that seal, and replacing the rubber parts at every tire replacement. I suspect that most of the "nitrogen leaks less" is because caps that seal, rather than dust covers, are used for most nitrogen inflation.
