I wish they did like in the 1940s… Instead, current directors cannot shoot proper B&W and just rely on hackneyed gimmicks (I mean stuff like using the overly contrasted shade of a Venetian blind, smoke going through a ray of light, …). There is always too much white and too much black, which kills the range in between, unlike old movies and TV shows which are made of shades of grey where everything can be seen clearly; settings are not adapted either; anyway they have no idea of what they are shooting, they simply shoot in colour and then remove colours in post-processing like they do usually when they apply their stupid colour filter (blue-brown = Scandinavian police drama, lovat green = Germany, yellow = Mediterranean, blue = techno-thriller, etc.). Any low-rated chain-produced family entertainment TV series from the 50s and 60s, filmed by a random director from back then, exhibits a better B&W picture than those modern arty attempts.
Even then… I mean, what has good chances to be OK is when the show is a pure serial with a defined story with a start and an end (so basically a looong movie cut in 40 minutes pieces), in a universe where the conditions of the time travel are clearly defined and limited.
When it is a series-serial mix (like >90% of TV shows theses days), with extra seasons which may or may not be ordered, you can be sure the writers will trip up, as they have to invent new things, and some of those things will break the conditions and the limits defined earlier and then it won’t make sense anymore.