I totally agree that pilots should glance at the ASI very frequently on
every approach. When students have trouble keeping a constant
airspeed on approach, I find it helpful to do a demonstration
approach, calling out the airspeed every time I glance at the ASI. Its
about every 2 seconds, as other people have said.

About doing 180 degree turns after a low tow failu I also totally
agree with writers who say the immediate question is 'can I land
straight ahead' and to do that if its possible. Training students to
automatically do a 180 degree turn at 200ft is teaching the wrong
thing. Some damage to the glider should be taught to be acceptable,
since its an emergency situation. Maybe training this at all is a bad
thing, since statistically some solo pilots are going to get it
disastrously wrong attempting it. One could argue that going more-
or-less straight ahead is safer, while attempting a 180 degree turn at
200ft is risking one's life to save the glider from minor damage, or
the club the inconvenience of a retrieve. One could say that a site
where a straight-ahead landing from 200ft will certainly result in
more than minor damage, is a site that should not be used.

I wonder how other countries teach this, and how accident rates
compare. I was taught to glide in the UK, in the 60s, on a winch.
When I could eventually afford aerotows, I was never trained or
practiced a 180 degree turn from 200ft. As I recall, the BGA training
at that time was simply a verbal briefing for a low rope break was to
land more-or-less straight ahead (or at my club, to fly out over the
valley). It was accepted that the glider might be damaged.
Personally, I suspect this verbal briefing to go straight ahead may
produce better severe-accident statistics than the US emphasis on
training low 180 degree turns.