Sometimes we are asked about other methods to break through these clogs. We use jetting equipment exclusively. Jetting refers to the use of pressurized water at high volume, guided and governed by specialized bits that break through clogs in pipes and flush away the contents thoroughly without damaging the pipe. A series of different nozzles and steps are worked through until the pipe runs fully clean from entrance to exit. Importantly, jetting will wash away all the heavy sediment and shingle gravel.
We do not use augers or snakes for this purpose. These are great for certain situations and can temporarily break through a blockage but without removing the rest of the debris it will usually clog up again quickly, if not immediately. With large root systems in particular they can often be removed as one long piece but only AFTER they've had all the surrounding mud and sediment jetted away.
Keep in mind that these extensions sit horizontally. They do not have a vertical drop or a lot of slope that's going to pull debris away just because you break through the initial clog and drain the water. There is never that "glug, glug, glug" satisfaction; these usually sit with water anytime it's rained within a week even if they're clean; they are low spots that naturally fill up. That's all normal as long as it's free to flow out when forced to, but it means they need more assistance to clear than most drains. Jetting, or controlled high volume cleaning and flushing, is the answer.