I love following the broad tangents that come up on this list...
I wanted to chime in on observatory use of sidereal time, and guider scopes, etc... At the research class instrument level, as is being pointed out (har har), pointing models are heavily used, for both first acquiring a source and more importantly to ensure that tracking the source is steady across the period the telescope is taking data.
Second, guider scopes in radio astronomy seem to be rare. The uses I'm aware of are usually used for coming up with accurate pointing model coefficients, by pointing at dozens of mag 1-6 stars all across the sky periodically. How often that is done depends on how stable the mounts of the telescopes are. For many radio telescopes, having a bright enough source in or near the field of view is rare enough to put it very low down on a priority list of control elements. Not to mention they're not much use in bad weather conditions that are otherwise okay for the frequency ranges a given radio telescope operates at, nor during the day, where even though you can see stars with proper filters, you're even more limited on how many you can see.
For our day-to-day use, sidereal is only used as a reference for knowing approximately what RA is up at that moment, which makes a visual sidereal display very useful.
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