I think right now the ability starts with 4 or 5 target-seeking anti tank strafes right?
No, it has 2 AT planes and 2 AI planes.
The AT planes attack on the first run. The AI planes do one pass without engaging before turning around and targeting infantry.
The AT planes will loiter and go for a second attack run if there is still enemy armor spotted within the ability targeting area. If they did the second attack run, they loiter for a third run. However, if there are no enemy vehicles spotted, they will leave the battlefield instead of loitering for the duration of the ability.
The AI planes do 4 (2x2) strafes in total (no loitering) and then leave.
So all in all the ability is more cost effective than Stuka Close Air Support as long as the enemy stays in the area for SA to do its full potential damage, but the planes will leave faster if there are no targets (they keep loitering longer in SCAS afaik). I think its higher cost effectiveness isn't that bad considering: it's the only lategame ability the doctrine has, the doctrine is very munitions heavy (Goliaths, JLI snipers, For the Fatherland, Sector Assault) so using Sector Assault is a strategic choice that will limit the use of the rest of the doctrine, and that the doctine pick is so obvious that the enemy has plenty of time to prepare and get some AA (at least in team games).
The only thing about Sector Assault that is overperforming right now imo is that the AI planes instantly pin whatever they are shooting at, which is more suppression than they were intended to do, but that is being fixed in the upcoming balance patch.