I don't think there is a general ideal fuel tube length.
Fast motors normally put more pressure on the exhaust system.
Also it can be used as a tool to make runtime, and make an engine fit the drivers preferences.
Normally I always try to go as short as possible because I like an engine which reacts almost instant since I also steer the car with throttle input.
But with the engines I'm running recently I had to lengthen the pressure system quite a bit (30cm of tubing + RB cooler) to reduce the pressure.
The pressure was so high it lifted the fuel tank lid by just blipping the throttle.
Took me some time to figure that one out.