Letting go is what you can live with.
That treshold is different for every seamstress. Mine is pretty high. I like a good finish inside and out. I take great care of finishing every seam, binding everywhere, matching motifs, stripes, plaids, attaching linings. I find that the garment last longer, is more washable and I love to bias bind hems, it's pretty when you sit down.
I am thinking about this because I read Very Purple Person 's blog post this morning about her recent green dress which she calls a fail. The dress is not a fail, I think it's totally wearable, nobody will ever notice the mistake and people are more likely to say, where did you find those green shoes! But I do understand her, I fuss over my sewing so much.
Case in point, this Ellen Tracy Butterick pattern I made in 2001. Now being wiser, I would notice it doesn't fit the model and stay away from it! Look at those gaping neckline and arms! (And No! I will never ever make plaid pants cut on the bias, this is such a receipe for disaster!)
Of course, I ended up with the same problems, you can see the gaping neckline still, I didn't know how to fix this one back then but I couldn't live with the armholes so I fixed them thus, which is not the way to do it, I know, but the dress was finished, I didn't have a dress form, I still don't have a full length mirror blah blah blah! It works, I could live with that.
But catasrophy, I totally ruined that dress when trimming the waist seam. One should never ever trim anything when tired : I cut a hole in my dress! Could I live with this?
Well, I did. I glued a tiny bit of fusible interfacing under it, it's partly hidden by the belt and since I made it 9 years ago, only one person remarked the 'hummongous' gash. The general comments are "pretty dress, where did you buy it?". I can live with that.