I had to make the hard call this morning after getting a wet patch on my arm as I was getting ready to leave. In the end I decided a 3x3cm patch was too much so I changed my shirt, was I wrong?
I think it is a sliding scale based on how urgent and important the thing you are getting to is.
If it is a normal day, a 3x3 patch is too much, if your application server is offline and everyone expects you to fix it......the 3x3 spot will dry and the smell is gonna be covered by you sweating anyway....