The last part of the tillering is just as slow, unless you neglect to use finer tools in which case there is a danger of overdoing it. The final finish is also a consideration so a finer rasp and files give a more appropriate finish.
The pic shows my tillering marks, I just slash across where wood needs to come off and put W on any weak points. The weak points aren't real faults by this stage, and the mark just shows that the bow is bending enough there. I use a fine/medium rasp to remove the pencil marks and then put it back on the tiller.
You can see my original W is now a point where I need to remove a little wood, this shows I've done a good job in evening out the limb.