As others have said, Nope - not perfect, not by a looonng shot! But it is getting easier and better. I am currently working on a fall wall hanging that has 8 Maple Leaf blocks and 36 Flying Geese blocks. I've tried to be really, really careful each step of the way for all the blocks and it's paying off.
I'm convinced starch (or Best Press) is awesome, as is very accurate cutting, pressing, and sewing. I bought an 1/4" edge foot for my Bernina last winter and it's made a huge, huge difference for me.
As for ripping out seams, I do rip and re-do if a seam is more than a little off. I don't think I've had to do it more than twice, and that's really rare. I do use pins if I need to, and I sew very slowly, using my awl to feed the fabric through carefully.
I have been known to toss a block and make a new one from scratch, but haven't had to do that in a while. Be patient with yourself, relax, and enjoy the process. As they say, Rome wasn't build in a day!