For me it’s never been a question of what I will do in public in terms of “comfort,” either my comfort level or others, but usually a bigger question is how quickly can i do it.
I’ve come to learn over the years that ANY activity that takes too long will turn those gears in a strangers mind and invite unwelcome conversation. I expose whatever skin, change a sensor, get out the big needle and do IM, or even IV of I can do them quick enough.
I should also add, that sometimes it’s a question of how inconvenient is it to get to a bathroom, or how dirty is the bathroom!