The way I do it (also explained somewhere in
here) is probably the fastest 'safe' way to do it. It's for sources where the pattern changes on commercial breaks but is otherwise the same in between them (save for a few scenes sometimes). I guess it's something of a half way point between just running tfm and calling it a day and just blindly using one pattern. You can decide if it's worth the small time investment.
Using cutter(->crop)->telecide->decimate is very fast (<=10 minutes or less on an i7 for a 24 minute episode). We don't need the matches from tfm so we can skip that and we don't need the scene change information from scxvid because we're making our own anyway at the commercial break boundaries.
You should be able to section it run pattern guidance on the sections (ctrl+alt+g). If one fails just set it manually (ctrl+t then ctrl+s) and go find the problem scene. This is where actually getting the metrics comes in handy because you can go through and look for high vmetrics (typically v difference on both sides and threshold set to ~30, threshold is source dependent) since we have the metrics. If you find something typically it's some random frame or an entire scene with a different pattern (ymmv). It wouldn't show up if we used tfm (we're setting a constant pattern for everything between commercial breaks) but there's no way to guarantee that tfm/tdecimate did the right thing for the entire source.
Set/do whatever else (cropping/resize/etc), save all overrides, encode. Make sure to use the
updated fieldhint as it's much faster (the old one didn't request frames lineally so it could get slow with certain sources).