How accurate is the REST API data for arrive/dep?

Not enough room for the full title:

How accurate is the REST API data for per airport arrivals & departures, *NOW*, during Covid, November 2020?

I checked the official website for Frankfurt International and see plenty of flights today. When I check the RETS API for the last hour at

opensky-network.org/api/flights/departur...31060&end=1605536450

I get an empty array (in the browser, and 404 when using my code).

However, when I push that back a bit, requesting for the last 6 days, using

opensky-network.org/api/flights/departur...18000&end=1605536450

I get a lot of results, the most recent being at 8:53p.m on the 15th of November - yesterday

Is there always a delay (if so, of how long), or is this some Covid/lockdown thing?

Thank you very much for that! Obviously, I did not search well enough. I had been trying to download as little as possible, to save the load on your servers

I am unable to set up my Pi 4disto, because I see only about one flight every week or two at the moment, so I will initially be unregistered.

I was hoping for information about a single airport, with maybe a one hour window. First, I planned to get arrivals & departures at that airport, then use the icao24 to build a state vector request (to reduce server load), taking some data from each type of API call.

Looks like my best bet would be to forget arrivals & departures and use only the All State Vectors API, but use a Lat/Long bounding box to reduce the server load. After all, I am not interested in every aircraft in the world, juts those around one airport (although my software may switch between airports).

Does that sound about right?

(I am off to read the entire forum now