Interesting suggestions, but I must admit it would probably not work work on my project (or on DS9 and Voyager taken from NTSC in general), mainly because of the problematic hybrid nature of the source material.

You have progressive and interlaced footage, both with different framerates, spliced together.

I even looked into many options so far: Telecine, then decimate; deinterlace, decomb, qtgmc, field blending, field bobbing, field doubling, discarded fields, swapped orders, even filters that were modified to either blend 24p with 30p or reversed by manually defining a framerate.

Nothing ever really produced the desired effect.

I guess I will try the PAL-discs now, since they have a professionally done 25 FPS, which is present uniform and throughout. Perhaps that will work.

But what bugs me most are the release policies by all those multimedia-corporations: I mean when we take a long hard look at how many times certain series were released, re-released, new editions done and then re-re-released again and so on, there was really no time or option to work on them so they could be presented in a standard up-to-date form (like constant framerate)?
Of course, I am no expert on the subject, but I would reckon’ this could be done automatically these days?

After all, we fans have bought so many releases and special editions, paid for so many streaming options and downloads, there was no money left to do this? Seriously???