The time to rejoin is 2 minutes.
If you are disconnecting often (over the course of the week) I believe the system will eventually prevent you from rejoining. Unfortunately, computers can’t read human intent, and that’s why they have a blanket penalty system to prevent bad actors (not 100%, of course) from abusing the leaving/rejoin functions.
More info here:
If you want to air grievances with the system, I recommend using Competitive Discussion, as developers do not monitor the troubleshooting forum. What we can do here is troubleshoot connection problems if that’s what you need.