I can cover (or used to before the bad knee and foot) that 21 feet darn fast and bet I still can if need to... 21 feet aint crud, especially if caught off guard.
Paranoid or experienced, I have more than one ready to go firearm around me at all times, holster by the front door, one on side of the bed, one beside the couch to give you an idea (Aint having a home invasion) and as a CCW permit (even thought I live in the free State of AZ) I carry ready to rock. That said, I would avoid a pull at almost all cost if possible and seeing it coming.
Last, right or wrong, if I feel a legit red alert for self or family, the threat will be eliminated. Period. I can do life in prison, I can not do life with a loved one dead for my lack of will......
Jim