Yes!!
On the ground during preflight planning you have to have a certain minimum fuel. Once the flight has started you can start to use common sense. What if you arrive at your destination, one with several runways and oké weather but a slight delay due to inbound peak. Your alternate has one runway and weather at mins?? There's no requirement to divert, the only requirement (and I'm not even sure if that's a legal requirement) is to be on the ground somewhere with final fuel reserve. If you anticipate landing with less it's an automatic mayday call