Taking his clothes off is time wasting for Sherlock.
Sherlock loathed wasting time. He absolutely hated it. That's why he always did what was conveniently easy. John soon discovered this one morning a few months into living with the man.
It had been late and John had returned home after his shift at the clinic. Sherlock was nowhere to be found so he presumed he was somewhere in his room. John could feel the material of his shirt stick to him. It had been a hot day and his tiny office was extremely stuffy. He needed a shower.
He walked over to the bathroom door and turned the handle. When he opened the door he noticed that Sherlock was sitting in the bath. John threw up his hands to cover his eyes. "Sherlock!"
"Oh hello, John." Sherlock replied casually.
"Would you lock the door next ti-" John stopped abruptly. Something wasn't right, "what are you doing?"
"Having a bath. Obviously."
"Yes, I can see that but…" John took in a deep breath. "You're fully dressed."
Sherlock was sitting in the bath. Still in his suit trousers and shirt. He didn't seem to mind. He seemed to be smiling too. Like it was something he usually did. "Oh yes. That. Well it was inconvenient for me to get undressed."
"It would take ten seconds."
"Precisely!"
"Lock the door next time." John sighed before turning around and exiting the bathroom. He reached back for the handle and closed the door. Sherlock was definitely going to be an interesting flat mate.