I never untie my sneakers when taking them off or putting them on. I will retie them when they seem a little loose. I have not noticed any extra wear and tear, but I do slip them off by hand.
Male from Augusta, Georgia
Male from the US. I used to untie, until I noticed a couple years ago that none of my friends untied theirs, and their shoes still stayed on their feet when they were laced loosely enough to slip on and off. Now I just leave them tied.
American female. I only untie the laces on the shoes that I can’t confortably slip on and off. So pretty much all of my shoes stay laced all of the time except for boots.
USA male…I untie before taking off…and tie after putting on. 
But…I try to choose shoe that require no tying…like van deck shoes.
Almost always tied. When I was at highschool and had to wear uniform I wore the same pair of school shoes for 4 winters in a row, I doubt they were ever untied in that time. If I get a nice new pair of vans I try to untie them for the first couple of months so I don’t tread the backs down and ruin them, but that good habit tends to fade pretty quickly.
Female, New Zealand
I always slip mine off tied (although a lot of the time they’re already undone or close to it already–my laces are always flapping around on the ground). I can’t remember the last time I actually untied my shoes to take them off.
Female, Ohio
Always untie to take off, retie after putting them back on.
Male, US of A
In the Winter, untied (I leave them at the door to avoid tracking stuff into the house). I usually untie them to put them on because I want them to fit right.
Male, US of A.