I'm beginning to not believe a lot of what Playrix are telling us. Not just with this but in a few things my experience is different to what they say.
It's been said that it's rare, although it does happen, to get more than 5 tasks on the board at once.
Based on team size, a solo racer gets 5 and a team of 20+ gets 5, (I've raced in both) so not sure how they work that out.