actually i take back a bit, on winterlake it seems a little harder than OB to keep/sustain momentum. i think because winterlake was almost a forced boost map because its flattish at parts. now with less boost power it does seem harder to keep your energy going forward. unless you hit the route just right, you're not going to be able to get back that easy.
of course, this could be a comment more about wl's map design.
however, on emerald, cavern, isle, seems like i can ski forever. note those are much more hilly.