I don’t buy clothes online but my wife does. This is how she works: She orders stuff all the time. Maybe every few days something will arrive and she’ll try it on. It’s like a constant production line so she’s never actively waiting to try things on. They “just arrive” constantly.

And yes she returns a ton of stuff. She probably visited the post office twice a week to return the non fitting items. Or a lot of times they fit but don’t quite look the same on her than she imagined or the quality wasn’t great.

Also some places she has ordered enough times from that fitting isn’t an issue any more. She knows their cuts and sizing very well.

I guess it also helps to be a standard size of traditional proportions. For myself I have to compensate for a more typical programmer physique haha.