You can calculate your position by triangulating from two
VOR stations. How many pilots do this? [...]

17,328, as of March 31.

Just kidding.

The intersections of two VORs are used for position in several ways...
one of them is finding ones position when lost. It's not much of a
"calculation" - it involves trying to draw two lines on the chart that's
half folded in your lap while flying an airplane, usually as the ceiling
is dropping, it's getting dark, and you have to go to the bathroom
really badly. A little turbulence doesn't help either. Once you find
where those lines intersect, you look down and see if you can recognize
anything that resembles what's on the map at that intersection point.
The number of pilots who have done this is pretty close to the number of
pilots that have ever gotten lost in visual conditions. This is
probably pretty close to the number of pilots.

A more common use of this triangulating technique is when flying
directly towards or away from one of the VORs; one can use the other VOR
to monitor one's position along the intended flight path. This is one
of the techniques used on an instrument approach to determine when one
is past a certain point (and thus able to descend further without
hitting anything). Every IFR(*) pilot has done this. However on an
instrument approach the intersections are predetermined on paper, and
one merely needs to know "is it soup yet?". You set the other VOR to
the desired intersecting radial, and wait for the needle to center.

The same is true when flying cross country under IFR. Very often one is
flying directly towards or away from a VOR, and intersections are used
to keep track of one's progress. Outside of a radar environment, they
are also used to report one's position to ATC, so they know when to let
other airplanes use the airspace you were just in. Sometimes one flies
to an intersection and then changes course to fly towards (or away from)
the other station. The technique is similar to that on an approach -
set the other VOR to the desired intersecting radial, and when the
needle centers, you're there.

RNAV (which can be based on VOR, DME, and/or GPS) has made it
unnecessary to actually fly directly to or from VORs - the computer
inside continuously calculates one's position based on whatever
navigation signals are being used. However air traffic control will
often require a pilot to fly the airway to keep things simple enough to
keep track of on the ground. It's easier (and safer) even in a mostly
empty parking lot to drive the lanes rather than cut across the parking
rows, especially if other people are also driving around.

When I fly VFR cross country (which means I can decide my route on my
own, without any input from ATC), I like to fly in a straight line, low,
and using pilotage (using landmarks) for navigation, so I don't pay much
attention to VORs. The practicality of a straight line course depends
on factors such as restricted airspace, terrain, and altitude. Slight
bends in the route don't add much to the flight, especially if they are
planned for (so the angular deviation is small). Note that a "straight
line" curves because the earth is round, and in most cases the compass
heading will be changing as you fly. This is an issue only over long
flights (say, several hundred miles). You can actually see this by
opening up a sectional (the VFR charts pilots use) and drawing a
straight line East to West across the entire length of the map. Compare
that line with the lines of longitude.

Flying IFR cross country, especially at the lower altitudes, I file and
fly the airways (which are generally to or from VORs) because the
minimum altitudes have been set out for me on the charts. Off the
airways, I'd have to fly higher to ensure terrain clearance, and that
might not be practical due to icing, or I might want certain altitudes
for other reasons (it's pretty to fly in and out of cloud). I monitor
my progress by tuning the other VOR to the intersections on the charts,
and watching the needle indicate their passage. At least until we got
the GPS. Now I watch the purple line, and back it up with VOR navigation.

Hope this helps.

(*)
IFR: instrument flight rules - the set of rules one flies by to avoid
bending aluminum when flying in IMC
IMC: instrument meteorological conditions - weather conditions that
requires one to depend on instruments to keep the dirty side down, and
requires one to depend on air traffic controllers to keep aluminum away
from you.
VFR: Visual flight rules - the set of rules used in VMC. Under VFR,
the pilot is responsible for avoiding hitting other airplanes. He or
she does so by looking out the window. And taking evasive action when
necessary.
VMC: Visual meteorological conditions - weather good enough to "see and
avoid" hitting aluminum, fiberglass, and granite.

Jose
--
Get high on gasoline: fly an airplane.
for Email, make the obvious change in the address.