@schratze @ramonita I can answer this one for the Netherlands, in case it's any help: you can demand that they contact your lawyer (make sure you memorize their name and city, if not phone number), and they can hold you overnight but will have to release you the next day if they do not have concrete charges to prosecute on (which they generally won't). Technically it's a set amount of hours but night hours aren't counted, so "next day" is what it becomes in practice.

There are a few exceptions; they can hold you over the weekend, and in exceptional cases they can get an extension for how long they can keep you. This doesn't happen that often.