In the episode "Darmok," from TNG, however, Riker orders Worf to take a shuttle down. This was while its still day time on the planet, but then we cut away, and even see night scenes as Picard is making camp. It's only after the commercial that the shuttle was launched. Why did it take so long?
To nitpick, we don't know what time of day it is in the planet when Riker gives the order. We might claim that our starshipside heroes only hailed the Tamarians after night had fallen on the planet, and then dispatched the shuttle without any delay - which would mean having to explain why the Tamarians weren't hailed immediately after Picard was kidnapped.
In several episodes of TOS, TNG and VOY, it appears that at least one shuttle is kept on a relatively "hot" standby, as indicated by the fact that a single person can steal one and fly away. In TAS, it even seems that sometimes up to half a dozen shuttles are kept at such readiness so that a theft can take place! Overall lack of preparedness thus sounds like a poor explanation for the delay in "Darmok".
Furthermore, it's unlikely that basic flight preparations (say, fueling the craft) would take the hour or so that it would take at a minimum to get from bright daylight to deep darkness, depending on latitude and speed of rotation on a plausible Class M world. Although here we may note that the surface location is surrounded by mountains, and darkness might fall fairly quickly, at high sun angles.
Two other types of "preparation" might be speculated on. Perhaps Riker wanted to install special communications gear to defeat Tamarian jamming, and LaForge had to build that from scratch because the type of jamming was so exotic... And/or perhaps Riker saw that there was no immediate need to intervene, what with the two captains apparently peacefully coexisting, and wanted to see what the Talarians would do next - and only when they did nothing did he risk sending down the shuttle.
Timo Saloniemi