I recently started to press my seams open and I find it makes it easier to get perfect matching seems. I also find it smoother to sew/FMQ. No lumps of seams.

I agree with what has been said, in general. When cross seams meet, however, there is a tendency for the fabric on top to be pushed out of alignment, even with a pin in place. Therefore, I have the seam allowance on top reach the needle before the seam itself. Sometimes this means clipping the seam allowance and folding it back to prevent shadowing.

I have done it both ways!

I always press to the side to butt seams. I rarely press open - only when necessary. I usually burn my fingers when I press open - OUCH!!

It depends on the pattern. I am working on the Charming Addition pattern which is pressed to the side. The Dresden Plate is pressed open. I consider the intersections and if seams are going to be thick I open them. I also will trim a bit of one side of a seam if there will be a thick intersection and it takes some of it away.
peace

I usually press the seam to the side unless there will be a great deal of bulk, e.g., pinwheels. Now that I am doing more FMQ, I may start pressing more seams open.

I almost always press open... I like my blocks to be as flat as possible.