So how long does it take to prepare for the ride, to put away the bike & how long would it take to walk? You're seriously getting into reduced returns territory.
Now you're changing the conditions.
I'd have to pack my bag anyway, and I'd have to walk up the steps out of my apartment anyway, and carrying the bike may take +30 seconds. The bike lives in the workshop at work, or chained to the bike rack outside, so it would also add +30 seconds, perhaps.
Google reckons it take 3 mins cycling or 11 mins walking, so I'd still be six minutes ahead if I ride.
Also, I could ride back for lunch, or make a small detour to get groceries on the return (6 min total, or 24 min walking)
Also, I get to ride my bike.
Inciidentally, on Monday and Tuesday I'm still riding 10k each way for the foreseeable future because I'm the reserve manager for another shop...