Without going into the icky details too much... yes it is relevant. Even something like grated carrots will sit in your septic tank for years without decaying. This is largely due to the temperature - it's far too cold to get the easy rotting and composting effect you would see if you left it outside in the sun. The solids you are mentioning are already digested, and are much easier for the bacteria in your septic tank to break down and reach a soluble/flowing state that can pass into your drainage field. Another good example that is REALLY common to see clogging the septic tank exit is coffee grounds - which would compost very quickly in the sunshine, but will last forever in your septic tank and contribute to a very thick "sludge" layer on the bottom. That layer never goes anywhere, and as it grows the capacity of your septic tank shrinks. This will go on until the sludge reaches the exit level and causes the septic system to fail, or until you have it pumped.