Wingnut writes:

"Often" is good enough for me.

It has not been good enough to prevent crashes.

The last time I checked, the altimeter is quite important when flying
(and doubly so when landing!).

It is called a _standby_ altimeter for a reason, although it presumably works
even when other instruments are working.

Important to know the plane's orientation,
both pitch and roll (while the compass gives you yaw, the third
rotational degree of freedom).

It's also important to know the current stall angle, the angle of attack, the
flight path vector, the airspeed and altitude trends, the V-speeds, the upper
and lower airspeed limits, the current track, the current route, the current
vertical profile, the current heading, the expected top of descent, and about
a zillion other things that a private pilot isn't likely to see in a tiny
Cessna.