Maybe now that I’m retired (from the navy at least) I should look into it? Probably a very low priority, though…
In my experience space-A worked well for a brief time for a specific destination.
Specifically for me that was in the early ‘90s when there were lots and lots of flights flying to and from the east coast of the U.S. to Germany, which was a pitstop en route to the Middle East to support the first Gulf War (and its aftermath). Also we still had a lot of troops in Germany itself at the time.
I quickly found out that another common stopping point was the Azores. If I could get a flight there, I could easily continue on to Germany or the U.S. depending on which direction I was heading.
My last trip to Germany in 1995 was a real pain in the neck though. There seemed to be fewer flights, and I was burning leave trying to get on one. I had never waited for longer than a few hours before, but this time it took 2-3 days. And being on active duty, I was the second highest category, second only to folks traveling on orders (which was rare). For example, if I showed up for a flight, I would get priority over dependents or reservists or retirees.
On one occasion on that last trip, I boarded a C-5, flew over the Atlantic for two hours, at which point it turned around because one of the two compressors that maintained cabin pressure had failed, and we weren’t at the halfway point yet. So a four hour trip to nowhere, and the flight team was going to exceed their allowable awake time, so the flight was scrubbed. I did eventually get to Germany, but encountered similar difficulties getting back. I very nearly had to purchase an expensive last-minute commercial ticket to get back in time to report to my next duty station, which is always a risk with space-A flights.
So I eventually decided it was more trouble than it was worth. Plus my wife at the time was very risk-averse and didn’t really like to travel, so she was certainly not going to try it with me.