Is it always possible to beat later levels on Hi speed?

Sometimes it seems like you get no holes in the highest row of germs and thus cannot clear horizontally. And I'm not sure exactly how the random piece generator works, but it's certainly not like Tetris because you can get several of the same in a row, meaning your vertical clearing options are limited too.

I'm more interested in a high score than speed run, but I'm not sure if it's futile to try to marathon the game if the repeating highest level (20 I think) is not always feasible based on randomness.

Thank you!