I have a Nikon dSLR that seizes up electrically if left with 70-300 VR attached for weeks. Fixes itself if left with a fresh battery and an 18-55.

I wonder how often that will happen with other brands like Alpha.

I used to have a Canon 40D with a 17-40/4 and later a 17-55/2.8. That camera would only be off when the battery was in the charger. Never had any problem whatsoever.

I can personally handle my A7ii with gloves, but no you can't always leave it on. I mean, you can, but not for much more than two or three hours.

I realize that I'm moving the goalposts a little -- here in Washington, gloves in the snow means soggy softshell gloves. Over time, my 6D has continued to build my trust that I can operate everything that needs operation when my gloves are squishy.

I first started using a full-frame camera in 2017 and looked hard at a number of options, expecting to wind up with an A7R-series camera -- the sensors are just awesome. I was coming from an EOS-M background. It was a revelation to me the first time I rented a DSLR and never needed to turn it off. I only turn the camera off when it is packed away within luggage.

One-handed case-open-grab-grip-up-to-eye-compose-and-shoot with gloves on was just amazing. No waiting... and I was practiced at switching on a camera as it left the case. Now, when I'm chasing wildlife, I can regard them through the viewfinder for hours without fear of draining the battery. The battery is only tapped if I hit the back-button focus or depress the shutter. I suspect my next camera will again be mirrorless, as the advantages are many, but if so, I'm really going to miss the always-ready capability of an SLR.