I've seen a lot of confusion regarding the "Quick Release" position (also called Füllstoß) on the Train Brake lever of (mostly) German locomotives in TSW. It is unfortunately named since it implies that holding the Train Brake lever in this position will speed up releasing of the brakes. This is not how you should use it. TLDR: "Quick Release" is a special function that opens a large valve between the main reservoir and brake pipe which sends a large pulse of air through out the train that will "nudge" stuck brake valves to release on older wagons. It requires skill, knowledge and special circumstances to use. If you don't know of these: Do not use it, except momentarily to release SIFA penalty brake on certain (Vectron) locomotives. The danger of using "Quick Release" incorrectly, primarily holding it too long, is that it will in fact cause stuck brakes. The only way to solve this problem after you've caused it is to either wait a long time (minutes) or go throughout the train and pull on the release valves. Why it doesn't work how you expect: From the unfortunate naming of the position it is not surprising that people think that it will release the brakes quicker. This is however not the case since the rate at which the brake cylinders (what are actually what controls the brake force) releases is fixed and only depends on the "Brakemode position" (G/P/R). For this reason, using "Quick Release" is more problem than it is worth for most users and situations. For more reading on both why "Quick Release" can create problems when used incorrectly and how to use it correctly, see my answer and this excellent description by JustusLM. EDIT: Removed the direct quote and added a link instead.
