Currently, colony fleet/patrol buildup is extremely opaque and almost entirely a guessing game. I have no idea how long until a colony's Patrol HQ (or any of the upgraded versions) produces a new patrol (or any other) fleet or what kind of fleet it's trying to produce, let alone how many fleets the colony has already produced and where they are or what their current composition is.
It would be super helpful if the Colony screen included a "Fleet Buildup" tracker that shows how many days until the Patrol HQ produces a new fleet, what kind of fleet it's trying to produce, and maybe a rough estimate of the maximum number of fleets/ships the colony can support given its current population, fleet base level, and any other variables that go into that calculation to make estimating your current level of potential system defense possible.
For bonus points, a "Fleet List" either on the colony screen or as part of the Command menu that shows a list of all active fleets produced by your colony/empire and their composition and current location would be very helpful as well.
I do also have an ulterior motive for this; my current colony has a high fleet strength rating (almost 100%) and Military Base with all its requirements fulfilled by in-faction production and yet has seemed to produce no patrol fleets after months of existence - I haven't seen any orbiting the colony or guarding the warp points, or flying around in the system. Only the odd trader fleet seems to have been produced. Having a fleet list or otherwise being able to see when the next military patrol should be built would help me figure out if this is a bug or not.