I have been considering a new video on sanding. I power sand only. The problem with scratches remaining is that you need to make sure you get ALL the previous grit scratches out before advancing to the next grit. I some times start at 80 grit, but usually at 100 or 120. I never skip grits. So, 80, 100, 120, 150, 180, 220, 320, 400 then grey synthetic steel wool for applying the finish. Like some one said, "Never take a finished piece from the shop to the house on a sunny day. Sunlight causes scratches." Learning to see the remaining scratches is an art. 150 grit is considered an extra step to some. It will remove 100 grit scratches, though slowly....
robo hippy
Are you sure that full scale of grits is necessary? I thought that 100, 150, 220/240, etc. were on a different scale than 80, 120, 180, 280, etc. The grit scales are usually a "50%" rated scale, meaning the subsequent grit would be 50% as coarse as the prior. Or in other words, sanding with 150 after 100, a 50% increase in grit (or 50% reduction in abrasive scale) would cut through HALF the depth of the scratches left by the previous grit. When you run through the full scale, each grit being 50% the last, then you eventually eliminate all the scratches, or at least, reduce them to a scale beyond human visual acuity.
I agree that you shouldn't skip grits, but, it seems like you are using two different grit scale systems together, which is doubling the number of grits you have to deal with? I would think that 80->120->180->280 (270 really, but 280 is the closest to the exact doubling grit)->400...would be a sufficient scale to acheive the 50% grit scale and sufficiently sand out all sandpaper scratches. At least, theoretically...
I could see using more lower grits, to make sure you eliminate scratches left by very coarse grits. That is part of the reason why I try not to start so low. I used to use 60 and 80 grit sandpaper, and all it ever seemed to do was shred my wood fibers and leave a FAR coarser, rougher surface than I was able to tool out in the first place. That seemed highly counterintuitive, so I moved up grits, until I found that I could generally start with 220, and sand out most tearout if I had any, occasionally falling back to 180 if I just couldn't get rid of all the tearout (more common on soft and punky woods, spalted woods, etc.) Then sand up to 400 or maybe 600 grit. I probably use 220/240, 320, 400 and 600 most of the time, and I guess that is actually a finer gradation than a normal 50% grade. I use these grits mostly because its what Norton sells, and I've found their sandpaper works really well for me.
I would have thought, that with power sanding, the need to start at very low grits should actually be LESS? I figure, if I power sanded, rather than hand sanded, starting at 220, any and all tearout would vanish within a couple of minutes? Once the tearout was gone, it should only take minutes to move through the rest of the grits...
I am truly curious if 80, 100, 120, 150 grits are helping, or hurting, if your tooling is good? Is there a particular reason you feel those lower grits are truly necessary to get the job done? Are you only using those grits, because once you use 80, and it puts big, obvious, deep scratches into your piece, is using the rest of those grits the only way to clean up the 80 grit scratches?
Just musing here... I think with good tool skill, starting at low grits could probably be eliminated, but, I only really have my own personal experience to base that on.
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I don’t turn many bowls but with careful use of a scraper some demonstrators have suggested you shouldn’t need to go coarser than 120 or even 150 grit. My problem is often getting a smooth shape straight from the tool, requiring some “Adjustment” with abrasives! 
