Unless I don't understand the operation of WC (not a rare event, of course) I think mine are updating every two minutes, just like several other pages do. Mine are on a separate page, but it seems to have the same pressure value as the direct read out in a text output page. I'm not at the Mac mini right now but I'm pretty sure that page is in the directory that is set to update every two minutes.
Checked the mini and the Custom Gauges are updating at 2 minute intervals, exactly as requested in the main prefs. However, the page that displays them only updates itself in the browser at a 30 minute rate. Since the gauges are quite a bit harder to view at the unit level, I save some data transfer rate on the viewers end by updating only 48 times a day. The detail info, down to a hundredth of a degree/1 mph/etc. can be more easily viewed as text on the main page.
Ar any rate, I know there is one other WCer who would like to use the Custom Gauges in Sierra, at least. The mini is still using El Capitan for exactly that reason. The Steel Gauges are nice, but I have my gauges like I want them without having to enable javascript. And the WC interface is extremely nice! Thank you very much!