for the fifth iteration of dwspd, the theme was build a co-op map in an outdoor environment. co-op isn't what it used to be, that's for sure, and if you're looking to play these maps in singleplayer, well you'll be prepared to noclip most of the time. only a few of the maps can be fully completable in singleplayer, others will rely on switches that will open faraway doors that you'll never ever reach in-game. combat of course is scaled to be much more difficult as it ought to be for a co-op map. I can see MAP01 and MAP05 being SP-compatible, and the same for MAP11 and MAP09 despite the slaughter settings and the switch that's so far away, but the others need at least two players. skip MAP04, this is a throwaway map with no exit. why is there not one, but two E1M8's? both are pretty average though, as is most of the set except MAP04 and Pablo's E1M8 which just fails the theme.
there's not a whole lot of co-op only levelsets and this speedmap set sure isn't the best thing you can find.