I would say that achieving a particular grade is a point along the way, not a change of direction. A new leg would imply a change of direction. That may be a different method of training or a change of instructors. What I was referring to was a point where you have the choice of continuing to train the way you were or leaving the path you are on and taking a different path.
Here is the word "leg" as defined in the Marriam Webster dictionary.
1
: a limb of an animal used especially for supporting the body and for walking: as
a (1)
: one of the paired vertebrate limbs that in bipeds extend from the top of the thigh to the foot (2)
: the part of such a limb between the knee and foot
b
: the back half of a hindquarter of a meat animal
c
: one of the rather generalized segmental appendages of an arthropod used in walking and crawling
2
a
: a pole or bar serving as a support or prop <the
legs of a tripod>
b
: a branch of a forked or jointed object <the
legs of a compass>
3
a
: the part of an article of clothing that covers the leg
b
: the part of the upper (as of a boot) that extends above the ankle
4
: obeisance,
bow —used chiefly in the phrase
to make a leg
5
: a side of a right triangle that is not the hypotenuse;
also : a side of an isosceles triangle that is not the base
6
a
: the course and distance sailed by a boat on a single tack
b : a portion of a trip : stage
c
: one section of a relay race
d
: one of several events or games necessary to be won to decide a competition <won the first two
legs of horse racing's Triple Crown>
7
: a branch or part of an object or system
8
plural : long-term appeal or interest <a news story with
legs>
The word leg, as we are using it, I would say fits the definition of 6b, "a portion of a trip : stage"
so you could say when you reach a new leg in a journey is a point along the way as you put it. You reach a certain point and then start on another portion of your trip or journey. That new portion can involve a change in direction or it might not. Much like if you're driving on a road trip, you stop for the night at a hotel, and then you continue on your trip. Your destination is the same, but when you reach the hotel and then from there continue on the rest of your trip, you could call that a new leg in your trip, but you aren't changing directions. The same thing with the martial arts. Although you can sometimes change direction in your martial arts training, that doesn't mean you always will and when you reach a certain point and then proceed forthwith, I would say that's reaching a new leg, whether you change direction or not. At least that's how it would best fit the definition of 6b.