AckE, if you were a long time reader of this discussion, you would know that for most cars, I rail against frequent tire rotations. In my opinion, frequent tire rotations increase the tire wear and hide alignment issues that increase tore wear even further.
On RWD vehicles, I don’t rotate, ever. On FWD, I rotate once when the front tires are a little over half worn, and then only front to rear, no side to side.
But as a Subaru owner myself, and a long time member of this discussion group and seeing how often Subaru (and other AWD systems) get damaged when tires of different circumference are used for any length of time, my recommendation is to rotate them on schedule.
This requires more diligence in inspecting for abnormal wear patterns on the tires just before the rotation so that any alignment issues can be corrected as soon as possible. Wheel alignment is the most critical aspect of tire wear.
Saying that, I am not a fan of frequent wheel alignments. Only do an alignment if there is evidence of the need based on driving issues such as pulling to one side or difficulty in maintaining a straight line, or if there is excessive tire wear. If it drives straight and the tires last as long as expected, do not align, but at the first sign of a problem, get it checked immediately and you will save money in the long run.
The case for using the severe schedule is much more detailed in the manual that the above listing. Read it carefully, it a page or so long. You may find that you are not in the severe category, in fact you are most likely not.
I would however consider getting the ATF fluid drained and refilled, NOT FLUSHED, about every 30k miles even though you are not on the severe schedule for that. It’s a small price to pay for really extending the life of your transmission.