When I first got involved in competitions in the 1960s all the gliders were wood, Oly 2s, Skylark 2, 3 & 4, Ka-6, 7 & 8, SF-26 and similar. Skylark 3 & 4, & Ka-6 were in the top class (I forget the name) with the rest in the lower class. A lot of tasks were from A to B via C if the wind was considered too strong to fly upwind successfully but in light winds there were closed circuit tasks and some were quite big, including 300K although that was not often. In one competition the top class was set a 300K triangle and the lower class a 200K triangle. We all landed out on the middle or last leg. A couple of us almost got back, having flown Westbury to Hereford in a straight line, across the Bristol channel and almost through the Welsh valleys near Cardiff! Those who went the inland and longer route via Cheltenham landed there! All the 200K gliders completed their task! The next day the tasksetters changed the roles and set us an easy 200K triangle and the Oly 2s, Skylark 2s etc were set a 300K dog leg race to Yarmouth. They all finished with most getting Gold distance & Diamond Goal! We nearly all landed around Lasham while those who did get back were mostly penalised for flying through the airspace near Heathrow! I recall there were some huge clouds between Newbury and London going into the airspace. Those of us who flew round them to the south found dead air, those who went into them got penalised as cloudbase was already in the airspace. A couple who stayed under them completed the task.
So, big tasks were, and still are, possible in those old gliders. And I still fly one and have lots of fun, and it will out-climb most of the modern gliders most of the time, just takes longer to get to, and usually arrives lower, at the next thermal.