I have had some root canals that were very painful while others were less eventful than getting a cavity filled.
Molars have several roots and are less accessible. One time I had a molar done and the instant the novocaine wore off I was in unbearable agony. I had to have someone else drive me back to the dentist as I was shaking so much I couldn’t even drive. The dentist apologized and told me that he had left one of the three roots for the next time. Needless to say, I found another dentist. Just make certain yours cleans out ALL the roots first time around.
Also helpful. Regardless of which painkillers they give you, take a few Ibuprofen also. It really reduces swelling and calms things down.
Secondly, don’t go running around as usual afterward. Just lie down or be as inactive as possible for several hours. This is when everything is most inflamed. No sense aggravating it needlessly till everything calms down.
Hopefully, your experience will be as benign as some of the less memorable of mine were.
Btw. Your description of what the procedure entails is basically accurate. One additional little tidbit. When they are cleaning out the empty canals, they are using instrument which are abrasive and designed to remove absolutely every trace of leftover infected root as possible. Sort of like a mini mini roto-rooter procedure. Hence, the swelling and irritation afterwards.
That’s how one dentist chose to explain it to me anyhow :)