You are correct. If dosed correctly it is a very safe drug. It is metabolized in the liver quite safely via combining with glucoronide and then excreted in the bile. However, in high doses all the glucoronide is used up and it then undergoes a different metabolic pathway which forms a free radical. The free radical is extremely reactive with the liver cells and kills them. Take a bunch of tylenol and it will kill you unless you get very prompt treatment, hours not days for the treatment.
The limit on the container is, I think, 2. If you take 3 Tylenol at once you are asking for trouble.
In fact, you should take every multiple medication with pauses between the pills. They do things in bunches that they wouldn’t do alone. My amateur but experienced advice, anyway.