1970 on a Wednesday, hmmm...
there's no rhyme or reason while Dave's away.
are you guys raising eyebrows here because it's usually Fridays that are reserved for 60s or very early 70s sets?
Does Dave stick to a map of sorts? Does this 1970 here increase the chances of some lame-ass 80s and 90s sets happening tomorrow and Friday?
Friday is, traditionally, the day for "old" years, usually '60s -- this dates back to the beginnings of 10@10 when they used to do "Fifties Friday". I always suspected it was an excuse for Dave to go home early, since the songs were so short, but clearly Dave likes to end his weeks with sets he really enjoys doing. Friday also became a day for theme sets like instrumentals.
ETA: I also always assumed Dave had a calendar of some sort of tracking board to make sure that years came up more or less evenly... but Greg told mshray that Dave goes totally on memory and instinct, iirc.