If, like me, you are under no commercial obligation to remove as much metal in the shortest possible time and are not subject to inspection or examination, then what works for you is the correct optimum speed which you can adjust to best suit the finish you want to achieve and to keep the chatter/noise down. I will, no doubt, be castigated by 'Inspector Meticulous' for expressing such an opinion, but I take the view that my workshop is 'my space'. Whilst I am working in there, there is no 'wrong way' or 'right way' of doing any job, there is only 'my way'. If I was working in a commercial environment I would, quite rightly, be required to work in the most efficient manner and to recognised industry standards, but the fact remains that this does not apply in the home workshop.
Again, and I can almost hear the brickbats heading my way, but in my personal opinion too many people seem to want emulate industrial production standards and textbook working which may be taken as a starting point and guide but adherence to which is sometimes hardly possible in the back shed . Whilst I always seek to produce my best work, I sometimes have to apply a little common sense, ingenuity and guesswork to what I do which for me 95% of the time works perfectly well. My apologies if this view offends some of the purists.