Ah I see. Sorry, misread the OP.
Did you have a rotating map board?
For MTBO (on an orienteering map, probably 1:15,000) you need one. As you ride along you rotate the map so that it is always orientated to the direction you are going, which makes it easier to read on the move.
At a trailquest type event (what they now call score MTBO !!) you are using a 1:25,000 or 1:50:000 OS map with more widely spaced checkpoints so fast nav isn’t generally so much of an issue.
Also, you’ll note that the Miry and others have the board mounted a fair way above the handlebars, which also helps.