I think you were right to use more oil and more pads on the 2nd half. When it's that dirty you end up just smearing the dirt around unless you are generous with the oil and wipe it off as you go. Also, if you use plenty of oil then the grime won't clog up the steel wool so much and you can use it longer.
One other thing: don't go too hard in one spot trying to smooth out a scratch. The natural pigment in the very top layer of wood cells darkens with age and it's easy to remove that to the point that it's noticeable. Just do a good overall job and then let it be for a week or so. Lots of times a scratch will darken alarmingly when you oil it, but then after a few days the oil soaks in and the scratch is barely noticeable.
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