So after seeing the way these enemy signal contacts work all the way through Admiral, and what they were like in the headstart as well as open and closed parts of beta I've come to the following conclusion:
The overpowered superfleets that spawn camp the warp-in zone while the instance is waiting to reset is intentional:
I have never seen any dev commenting on this as something that needs fixing, over the constant posts of players asking WTF is going on with this situation. There can be no other conclusion except that this is something that they don't believe needs fixing. Why would something like this be intentional? Perhaps to clear out the instance while it resets? To shoo everyone out, like theater attendants after a movie ends?
Why does the instance have a 6 minute reset timer anyway? The only thing I can think of is some sort of back end work that we don't see as players while the enemy units respawn, perhaps waiting to get a new instance ID# for the database (not the actual instance number, but some sort of database-only field for database record identification, although why it needs 6 minutes is beyond me).
A better "fix" for this, if the superfleets camping the spawn points are indeed intended, is to STOP HAVING PLAYERS ENTER INSTANCES THAT ARE WAITING TO RESET. If players want to sit in an enemy signal contact instance all day long that's fine, and you can have the super patrols roaming around while that instance is waiting to reset, but let's knock it off with having new players come into an instance with a battlefleet already on top of them when they come in.
I know as it stands now, If I enter an Enemy Signal Contact and see that there is anything over a minute left on the reset timer I immediately warp out. Anything more than that is a waste of time, and there's probably a super battle fleet two seconds from weapons range waiting to insta-gib me over and over again until the reset timer runs out.
As far as I can see If I get warped into a zone and there is a fleet already there, there is also indications of a fight that is happening or just happened, I beleive that they get drawn into the area, usually after a zone is in reset, if you die and do not respawn they will move away, Also when the countdown timer ends a lot of the time they will despawn
The reason for the countdown is to prevent you from just staying in the area and never leaving, at least with the countdown you are forced to either wait or warp to another zone, plus the time allows you to prepare for the next round, add new weapons to your ship, or form a team.
I'm with the OP on this one. There doesn't seem to be any rhyme or reason to the way those encounters work. Feasibly, the big glowing nebula-looking things should indicate a fight in progress and the single ships flying around should indicate a fresh fight, but this isn't the case. I've been intercepted by plenty of enemy contacts, only to warp in and see a message telling me, "Good job, fight's over."
I suggested this in another post, as I thought enemy signal contacts were broke.
Make 2 kinds of sector signals. First is a solo player signal. It is invisible in sector space and tuned to a single player encounter. It has a small chance of spawning a named ship that drops rare or better loot. This encounter is a surprise encounter, you never know when or if it will happen.
The second encounter is a group signal contact. it is visible on the sector map but can only be engaged by a party. It is tuned for 3 to 5 players working together and has a higher chance of spawning a named ship that drops rare or better loot. You cannot solo this contact. You cannot go charging in ahead of your fleet mates and survive.