A normal European tourist situation (visa) is roughly 90 days. Then you leave. Some countries might pretend that one day out is enough but the rules generally specify that you must remain out for 90 days before you can re-enter. The Schengen treaty specifies all of this. If you want to get around it....you walk in and do the full up visa with paperwork and show intent to stay around. That also implies taxation, your ability to pay for health care, etc. When you look at Hollywood stars who spend time in Europe....they all try to stay within the limits.
The UK isn’t one of the Schengen countries, so not sure that’s relevant to this case.