I treat all these greens as cut-and-come-again plants, always cutting from the outer leaves and leaving the growing centers intact.
We have lots of volunteers too.
I can't think of anything more useful for a home garden, except maybe tomatoes. There's just no comparison between the weeks-old bagged lettuce mixes and the minutes-old lettuces from a garden. It's so easy and we have plenty of greens for huge salads with every single dinner, sandwich fillings, and green smoothies.