I have Subaru Impreza 2011 2.5l Premium Manual transmission. Third generation. EJ25 engine? Pretty certain that's the one.

So, tradition says to keep it under 3000 rpms. But tradition isn't always correct in all circumstances. Cars have evolved since this rule of thumb was devised. I'm pretty diligent with toping off the oil, as it does burn a quart every 500 miles or so. Which is kind of annoying, but w/e.

1st gear 0-15mph, 2nd gear 15-25/30 mph, 3rd gear 25/30 - 35/40 mph, 4th gear 40 - 45/60 mph, 5th gear 45/60 - 75/95 mph.

We don't have an <3000rpm tradition in the UK. It's only just alive at that point. Is Miss Daisy your passenger?

True ,2.5l sti match diesel top rev band/power , best to stay below 3k revs
It has to reliability of f1 engine

Personally, I think it's far more dangerous to lug the engine in low revs.

My car sits at 3500rpm on the motorway at 70mph. No way to stay under 3000rpm if I want to go the speed limit.