I "lost" my Mark overnight once due to her being flighted and 'operator error'. Since then I keep them trimmed, because we are always coming and going and need the peace of mind knowing they won't slip out the door, or get far if they do.
Before that (when I didn't live on a busy farm) I used to let Mark's wings grow out in winter, when we were indoors mostly, and doors usually shut. We'd have a few flight lessons to get reacquainted, but she was not very thrilled with flying for the most part.
Lucky came to us trimmed, and we've kept her that way too. She's pretty nervous and busy so her weight doesn't get up there.
It's a personal choice for sure, and based on how traumatic it was to lose Mark, just for one night, I'll play it safe when it comes to flighted birds.