No, the gains from CBTC come from two factors: one, it being a moving block system, rather than an absolute block (really you can think of a moving block system as an absolute block one where the length of the block approaches zero), so spacing matches the braking distance required; secondly, as with many modern in-cab systems, it is down to the individual trains to compute their braking curve, rather than the length of the blocks being dictated by the worse-case braking performance of any stock on the line.

I'm also unaware of any freight or mixed traffic application of CBTC, which makes it a stretch to say every railway should, though plenty of proven in-cab systems provide many of the same benefits (and you can decrease block-length substantially to get much of the way there).