The rows are randomly generated. each row has a total they add up to (at the begining is 105 and increases by 30 every 6 levels) and that number is distributed randomly amongst the 6 obstacles on the sides (with health limit obiously) , and the remainder is sent to the center (this one does not have limit). Generally, if they are too evenly distributed the easiest obstacles to break are the ones on the edges. You gotta react fast though (and may have to do a full spin to fully pass).
once you start using the Unlocks, you should be able to break through obstacles with ease