I'm 4b if that matters. For braidouts, I braid in smaller sections and "tight", not tight to the scalp but down the length of each braid. I also braid with a product that gives light hold. Kinky curly knot today with oyin handmade burnt sugar pomade works for me. I tend to leave the plaits on for a day before unbraiding into the braid out so that it sets. And yep, I get a week out of that, just tie my silk scarf go to sleep and in the morning after my shower, I take off the scarf shake and go.
For twistouts, I'm currently finger detangling a twist out I've worn for this past week. Still looks good by the way but I'm tired of it. Anyway, I had my hair in tiny twists which I wore for about 3 weeks, washed on the third week then undid the twists to wear a twist out on the 4th week. That 3rd week wash was key to holding the twist sections in place
So key things for my "out" styles are braiding/twisting in small sections, a product with hold, twisting/braiding a little tighter, and wearing the original braids/twists for a little bit to allow the style set. My 4b hair is pretty good at staying put.