The point gaps along with the points cam profile set the dwell or charge time of the coil. While the coil doesn't always need to be fully charged, the actual dwell time (rather than the crank degrees of rotation) reduces with higher RPMs, as the crank completes a rev in less actual time, which reduce the time the coil has to charge up for the next spark event.
You can fudge on the gaps and still have a bike that runs. But, you are relying on extra engineered margins of the parts and design to get a good reliable spark in the stock system. The margins naturally erode with point contact resistance increases and wear, and weak batteries during electric start operation can make the spark less than optimal as well as electrical connection that lose voltage. Further spark plug electrode errosion, widens the gap and make higher spark voltage a requirement. (These are also reasons for periodic tune up intervals.) If all the design margins are consumed with shoddy,fudged adjustments and other ailments you are asking for eventual reliability issues.
Also, I don't agree with setting the timing at full advance and ignoring idle timing. That's a procedure developed by the electronic ign. aftermarket salesmen. If you can't get both idle timing and full advance timing on your point system, something isn't working right and should be repaired rather than ignored. Of particular concern, is if the idle timing isn't identical for the two sets of points. This WILL lead to lower end trans rattle/gear clack at idle as the cylinders fight for crank rotation speed domination. But then, if you also fudge on idle speed setting by upping it higher, this problem can be masked. too.