Just in case there's anyone who is struggling with reaching high point combos the old-fashioned way, I wanted to point out that there is (currently) a Created Park called "Roller Coast" that makes (at least this one) SUPER easy. [Not sure who created the park as the park details list "---" as the creator ... certainly wasn't me].
Once you get the grind started on the rail angled upwards (you'll know it once you're in the park), it's really just a matter of holding
to keep the grind going. The rails are setup in such a way that they're short segments so left/right balance doesn't come into play, and the multiple will be pretty big for the number of rails hit.