Isn't every 3-4 months the standard title release cycle anyway? - 3-4 titles per year equals 1 every 3 to 4 months.
As for the drawn out production cycle for ACDC, this was in my view entirely planned by Stern as a deliberate response to WOZ to draw as much attention away from JJP just as the WOZ production cycle was "ramping up" and the increased interest would boost sales over and above the LE 1000 and into the regular WOZ production run.
The first Pro's hit Aus in what January and it is now the end of April? Marketing 101 create a sense of urgency/demand with your consumer base by drip feeding product to them.
ACDC was always going to sell well given the pinball demographic, regardless of gameplay. As long as Stern included the standard core songlist as a soundtrack on permanent rotation, then gameplay will usually takes a backseat.
I've said it before, but 80% of the ACDC layout was already designed as a rejected Avatar template back in 2008. Not trying to be a downer to those who have laid out the cash for one, but it is what it is.
Stern wants to be the only kid on the block again, that way they can go back to cutting costs (plastic pegs) and effort (unfinished code). They know these LE prices are not sustainable amongst the home market in the long term, (for argument's sake to round out 2012 - Avengers, X-men and MIB LE versions at 9250 apiece who's buying?) but they need to squash their main opposition before they can.
In the meantime, squeeze what you can out of the home collector market until there is nothing left to squeeze.
The only positive I have found out all of this, is that it makes a restored Bally Williams A list title in the 6-7 range a bargain.