Space-A traveler guide
The strongest Space-A plan assumes the military option might disappear. AMC explicitly warns travelers to be prepared to pay for commercial travel if schedules change or become unavailable.
Choose a stop-waiting date or time based on the event you are protecting. If missing a wedding, cruise, medical appointment or return-to-work date would be expensive, switch to commercial travel before the backup itself becomes risky.
A second military terminal is useful only if you can realistically reach it, stay nearby and still recover with commercial travel. Historical route activity can help identify candidates but should not be treated as a future schedule.
Include lodging, food, rental-car or rideshare costs, baggage, parking and the commercial airfare you might buy late. A free military seat can stop being the cheapest option if the fallback becomes expensive enough.
Quick answers
If timing matters, yes. AMC explicitly tells Space-A travelers to be prepared to cover commercial travel costs when schedules change or disappear.
Set the cutoff before travel based on the hard date you cannot miss and how long the remaining commercial options stay practical.
They can identify terminals worth watching, but a historical route is not a current mission. Verify the terminal's present schedule before repositioning.
Official sources