Very much correct usage for a light 'Mech, i think. Not illegal at all. There is no rule to take shortest route possible, jumping movement being the sole exception (and that has an additional exception of playing with Design Quirks and a 'Mech has Nimble Jumper).
While BT round (10 seconds real time) is split into phases, the way Target Movement Modifiers work is that they essentially simulate attacks and movement happening both at once. Trying to hit a 'Mech zigzagging everywhere is difficult.
WE had one player try to make it seem one could go back, forwards, back, forwards, back fowards and so on, JUST IN their Walk MP limit, and have THAT count as moving multiple hexes for his TMM...
BUT in general, i've seen it as Contiguous hexes.. So you go say 3 straight, turn once, two more hexes, turn once more, 1 more hex, turn once more, then 2 more hex, using up 11mp...
A lot of stuff to consider. TMM thresholds are good to remember: 3, 5, 7, 10 (18, but this is not exactly common) hexes moved. If you can, getting highest possible is usually good but attacks should be considered as well. Does moving 7 push you to range where your weapons are no longer at short range? In such case, it might not be worth getting higher TMM, because at medium range your weapons are at +2, probably not a good trade for +1 TMM. Also consider where does your movement end. Heavy Woods are pretty much always good, losing higher TMM threshold because you moved to one nets you +1 additional defense.
And you may wish to consider your next round. Where can you get from your planned ending hex? This is especially important if you lose initiative and end up in defensive, having a fallback position is useful.
Also, if you are using "You move one, i move one", THINK OF who's moving AFTER you.. SO you don't leave your back open!
Another good trick is to run past your opponent on a side where they have no arm-mounted weapons. They can torso twist and use one arm to cover directly behind them on the one side, but the other side is blind. To-hit numbers are irrelevant if the enemy has no guns that they can bring to bear. In some cases, you can line up a back shot from one hex to the side of their rear facing and 2 or 3 away, so you've got a freebie shot at their thinnest armor with no return fire. In other cases, it may pay to go for the point-blank back shot from directly behind them anyway, then follow up with a physical attack. I've killed a couple of assault 'Mechs with a Locust that way (fire weapons, then kick and hope they fail their piloting roll). Granted, I've also lost a number of Locusts.[/quote]
Done that before.. Ran up beside someone, turned around then came back on his OTHER side (which was his non-weapon arm), so couldn't get shot back..