Usuing the Rodgers technique I never found that to be a problem off duty for EDC. When I was doing entry’s(room clearing ETC.) I had a light on my handgun. Most of the time I used a suppressed HK MP5 which had a light also.The problem with a non weapon mounted light is now you need to draw two separate tools for one job. Also not having a dominant grip on the firearm because your holding a separate flashlight can be more of an accident waiting to happen than possibly aiming at an unintended target. The only time I'm pointing a firearm at someone is if there's a chance of an immediate threat. Keeping a separate handheld light on your person isn't a bad idea but to rely on it while in an engagement is asking for trouble.
If you have both a weapon mounted light and handheld, It's a lot easier to train to drop what's in your non draw hand and use the weapon mounted light then it is to use both tools at once.