No, I don't leave them loaded around the house. I like to know what ammo I'm shooting, and random loaded mags are hard to keep track of whats in them. I keep one mag loaded in my home defense gun. If I need to 'grab and go' then I can grab both the mags and ammo and load them up later.
You can label your mags as you load them. this will remedy that issue. If you're loading them yourself, you should be able to tell by the first round in the mag what ammo is in that particular mag anyway.
When at the range I load them up as I need them. If I'm at an outdoor range, the ones I frequent require that the whole range go cold to change targets. I usually am done shooting a target long before that time, so I'll stop and reload all my mags.
At an indoor range, the pulley that puts the target out induces a bounce when I run the target out that takes a while to settle down. I use that time to reload.
IMO that just takes extra time at the range, and on a busy day I prefer to shoot and go, instead of taking my time reloading mags one at a time. If you have 4-5 mags or more that can take a while...