Hmm there are a lot of potential scenarios. Two personal examples.I'm an Indy, I do not book hotels unless I'm touring, and if you entered the building before I told you would be sent home for not following instructions designed for my safety and for discretion ;-)
1. One time buzzer broke, I told the security a story of meeting someone in the building to purchase something from Kijiji, and was able to go up to see the lady.
2. There are several people trying to go in, instead of waiting like an idiot, I took a quick glance and noticed security wasn't there, so I followed everybody instead of waiting outside to buzz.
Your instructions may not work all the time. Be flexible and reasonable is the key.
If somebody drove 2 hours to see you, and you sent him home for not "following instructions", he might be so pissed that he would post your condo address, room number and buzz all over the internet, there goes your "security and discretion", all because you pissed off one client.