At a glance, I do think 5 minutes is too short for in tournament breaks. I think really needs to be 8-10 minutes at a bare minimum, maybe more if the tournament is bigger.
I would endeavor to start the tournament as close to the announced time as possible, but definitely have a "doors open" period of 20-30 minutes before that point. Then people can buy in right away and then chat among themselves until cards fly. And yes, it's important to respect when big moments are happening during games, but outside of this, plenty of time for banter.
FWIW, I am planning a tournament in August. I am advertising doors at 6, start at 6:30 (though really I will be happy dealing by 6:40) first break is 18 minutes (same as a full level), later breaks are 9 minutes (half a level)
Our events are usually multi-table social affairs, that run thusly...
5:30 Doors open, Dinner is served. Pregame food really encourages early arrival. It is not Hot Dogs.
7:00 Cards in the air. This is very timely. We rarely have anyone show after 6:45, and when they do they have reasons (one owns a nail salon, and will sometimes have a late client). I think one of the marks of efficiency is hitting your timing marks. If you never start late, players wont show late.
12 minute breaks every hour. It takes about 10 minutes for the average smoker to burn a cigarette and I don't allow smoking in the house, so anything less than 10 minutes is senseless. We usually play tournaments, but occasionally host a cash game. We take breaks in the cash game too. This allows me to top off short stacks without interrupting play at my table, and allows more interaction between guests playing at different tables. Many eliminated players will use the break to say their goodbyes without interrupting a hand.
The last break occurs when down to a handful of tournament players, and this break is often skipped if the players agree. By 11:30, everyone is full
Game concludes between 11:30 and midnight, depending on chip set / blind structure used.
Doh, I just double-checked and my breaks are set at 10 minutes. Currently it's:
B3 + chip up: 10m
B4 + chip up: 10m
I'll try squeaking the first break up to 12 minutes and see if that's more comfortable.
Later breaks do get skipped...last game I could only muster 8 players and the tournament seemed to play a lot faster...by break 3 we were skipping the break and only had a few players left!