Realizing the cars age plays into this, but wondering and curious. Seems more often than not, every time I go in for an alignment check, I need one, but to qualify this I will say the roads in my city are not good. I try my best to avoid potholes, mostly succeed, sometimes not. But is it fair to say it doesn't take much to put this older Forester out of alignment?
So much depends on the condition of the vehicle.
That being said, most vehicles will tend to keep their alignment for quite some time (easily a year or more) barring substantial impacts with curbs or particularly vicious potholes. Is there something your Foz is doing steering/tracking-wise that would make you suspect you need an alignment? Are the tires showing abnormal wear patterns (tread feathering along the outside edges of the tire; uneven wear across the tread; whatever) that could be a clue to an out of alignment condition? Abnormal tire wear can also be a result of bad shocks and out of balance tires. Obviously if both steering/tracking and abnormal tire wear are present, then it's a very good sign you probably need an alignment.
To simply stop in and get a "free" alignment check (or add it to a service visit) just because ...well, you're setting yourself up. I mean think about it; the only way to "check" an alignment is to do all the set up work necessary to
do an alignment. And all they have to do is find one spec that might be a little sketchy or possibly claim some tire wear and, bingo, you're on the hook for an alignment. When you ask for an alignment check, do they ask you what the car is doing to make you suspect it needs an alignment? If they don't, then I would seriously consider going to another shop. Because this one is probably gonna take you for a ride ...on the alignment machine. Whenever you get an alignment,
always ask for the before and after printouts ...most reputable shops will include this with your repair bill receipt without you asking; if they don't, then find another shop or ask why they didn't include it. The print out graphically displays the alignment of the vehicle as brought in and shows what the shop did to correct it and indicates the alignment of the car coming off the rack. It's the closest thing to positive proof you got what you're going to pay for.
If your car tracks straight, doesn't pull, and your tires are not showing any abnormal tire wear ...then, like the old expression; if it ain't broke, don't fix it.