Is defense necessary in practice rounds?

[Btower]

From the tournament manual.

8.2 PRACTICE ROUNDS
8.2.1 Schedule
The Practice Rounds will be played all day Thursday. The Practice Rounds schedule will be available on
Thursday morning. Practice Rounds will be randomly assigned. Each team will be assigned an equal number
of Practice Rounds. At some events, additional rounds may be available on a standby basis. Each Practice
Round will consist of a ten-minute period in which teams may operate their robot on the field. The first five
minutes of each Practice Round will start with a 10-second autonomous period, and followed by a “free-form”
session, in which the robots may be exercised to evaluate operational characteristics, gain driver experience,
determine system robustness, etc. The second five minutes of each Practice Round will be conducted as a
“match” with approximately two minutes for set up, two minutes and fifteen seconds of regular game play
(including autonomous operations), and one minute to clear the field.

So I'd say defense is necessary and allowed within reason. Thankfully, I'm the one who gets to decide "reason", sorry.

Seriously though, should we make an field announcement, say at a drivers meeting prior to the start of practice rounds?

On a second practice related topic. Should we allow team extra practices on a standby basis, if another team does not show?