My 605K score never left stage 4.

The way I did this was simple...

-> Discover the fastest way to group the enemies
-> From there the fatest way to lead the group down to the leeching point

If done with razor sharp timing all four enemies will constantly populate the leeching spot. And if you can keep up the button mashing, you can juggle the two athletes in place for large blocks of time,,,and then the score really starts to climb. A second off in the path leading down and your score per life diminishes substantially.

I envision 700K is remotely possible this way if, on all lives, the group of 4 enemies is properly lead to the leeching point.

Playing it out normally, I can get up to the 6th stage only.