I disagree with this. People paid for certain parkours, and if suddenly defaults could do the parkours too, then it would;
a. Make people with ranks angry
b. Defeat the purpose of a rank in parkour.
c. Be unfair to people that already have ranks.
There is also a fundamental problem with your idea. Say the parkour of the day is Ice Parkour. (Ice parkour is very hard to complete, and has six checkpoints). A day isn't enough time to complete a parkour like Ice Parkour or Rise of The Butter King parkour. Also, say you DID manage to complete one of these parkours, somehow, since you could access any checkpoint in the parkour, then you could return to that parkour any time you wanted, which would be even more unfair.
When you say "Make it fair for defaults", that suggests that it is already unfair for the defaults (obviously), which is untrue. People with ranks earned their ranks, either through paying, or from voting a heck lot. The defaults shouldn't get those parkours if they didn't earn it. Other people with ranks did earn it, and it would be unfair to them.
This would be sort of like saying, "Hey! Everyone gets Mockingjay now!", but less extreme. Of course, this would make all of the Mockingjays ticked off, because they got the rank through something, but everyone else got it through it being free.
I agree with Trenly and the Staff.