We have spaces of 12 months, 14 months, a couple around 1 1/2 to 2 years, a couple around 2 1/2 years, 3 1/2 years, 4 years. Each spacing has its difficulties and it's great things.
For the smaller spacings, the first year or so was hard since both kids needed me for everything and I was very tired with waking infants. But as they got older, they easily became best friends and played together well (mostly - some personality differences have caused some issues, of course).
For the larger spacings, it was easier at first since the older was independent before the younger was born but as they grew there was more difference in interests and developmental stages so they didn't become friends as easily. And, in one case, the younger spent most of his life trying to catch up to the older and being frustrated and angry when he wasn't able (the child's personality is the "grass is always greener in the older ages" thing). But now that the older of the two is a young adult and the second is almost there and our biggest kids at 6'3", they get along great and enjoy much of the same things.
So I would agree that it always works out. Don't overthink - just enjoy. It goes much to fast!