One of the most important aspects of completing the barrel boards is being able to progress up the screen as quickly as possible. One of the biggest obstacles to this is having numerous barrels blocking your path at the top of ladders. Much of this can be alleviated by steering down the two long broken ladders (one connecting the 3rd girder to the 4th girder on the left side, and one connecting the 4th girder to the 5th girder on the right side).
If you are stuck on the 3rd girder, simply steer barrels down the left broken ladder as best as you can while waiting near the middle ladder until an adequate space in the barrels opens up. Likewise, you can do the same thing to go from the 4th to 5th girders. If you practice this skill, it will soon become second nature. In general, steering down these ladders (as opposed to simply ladders that are close to you) helps give you even more space between the barrels above you. Realizing that you have significant power over barrels -no matter if they are on the other side of the screen or even levels above you- will allow you to feel as though you have complete control over the game.
By the way, you can even steer barrels down these broken ladders while you are climbing on another ladder; this allows you to scale the stage even more seamlessly! When you aren't playing a serious game, it is very helpful to practice coordinating several different methods of steering the barrels from several different positions on the screen so that they become second nature and you may perform them at will without any fear.
(P.s. Allen Staal, if you read this, read it 8 more times^!!!!)