Yes Tenacity, I'm down with the time lag, too. It adds the spice of dramatic tension to some great episodes.
One problem with this idea is that once the TV show establishes that communications are lagged, then they might be hand-tied in the future when they want to tell a story that includes instantaneous communications with Starfleet/a star base.
But there is a way around that issue that could let the writers have the best of both worlds. Here's my possible way that the DSC writers could have it both ways as the story suits them:
Let's say that subspace communications (whatever the hell that is, exactly) could travel instantaneously, but has a limited range. A possible way Starfleet gets around that limited range range problem is by setting up a system of subspace communication relays -- i.e., signal repeaters, not unlike mobile phone towers. These stations could be set up distances from each other that are within the limited range of the subspace communications, along a signal to be instantly relayed for one point to another, even if those points are further apart than the limited range of a subspace message.
So that's how the writers could give the
Discovery crew instantaneous communication back with Starfleet if the story calls for it....
...HOWEVER, what if the story would be better told by the writers if there was a lag in communications? How could they reconcile the idea of a lag with the previous precedence of instantaneous communications? Well, there's a way to do that, too.
Let's say that the Discovery (or someone else) is in a part of space that is lacking enough subspace communications relays, and they a thus too far from a relay station for the subspace signal (with my hypothetical limited range for it) to reach it. Other non-subspace signals (still FTL, but not instantaneous) could still reach the relay -- and once part of the relay would be sent along instantaneously -- but there would be a time lag to and from that original entry point onto the relay.
