You never really want to be waiting for anything or only doing one thing at a time. So, if you're scanning a machine with Nmap and see it's running a web server, go ahead and throw something like Nikto at it. The more info you obtain the higher your rate of success will be. If you pop a box don't let it sit there, use it! Use its cycles to crack passwords or maybe you might find something interesting you could use as a social engineering attack. If you get into a machine using a certain exploit, other machines may be vulnerable to the same attack if they're not working as a team and helping each other secure their systems. Use the lack of communication to your advantage :)
USB attacks are great. Drop a few USB drives with some value added features around and see what you get ;) Just be sure to inform your teammates :) Which is another thing, if you have a team, be sure to help each other and keep the communication flowing. Also, be sure to keep documentation ;) You'll definitely want the instructor to clarify the rules of engagement so you don't do something that gets you disqualified or something lame like that.