If I ignore the tonnage bar and the orders will there be other ships out there?

[jscharpf]

Since many seem to have issues with the tonnage bar, what if I just ignore the orders and sail out to the western Atlantic. Why should I care if the tonnage bar doesn't fill up? Will I be penalized for not patrolling ONLY on the east side of England?
In SH3 I could ignore the orders to go to a certain grid and still find plenty of ships elsewhere.
I'm still trying to understand why I should worry about "advancing" to the next phase.
What am I missing?

Jeff