[21]

No it's not. There are other sources of randomness around - color of card on table, ...

Don't assume pro players are so stupid as to fall in such a simple trap.

[Twirrim]

That's not the point they were making.

The point was that if you're going to look at the clock and use the second hand to help you make decisions about whether or not to bluff, look at it at other times too when you're not making a decision, so that looking at the clock doesn't become a tell.

[xapata]

You should consider bluffing on every action. Otherwise it's not random enough.

Not all bluffs are wild all-ins with deuce-seven off-suit. Some bluffs are a bet instead of a check, or a bet slightly larger than typical.