Perennializing lettuce and other annual greens?

In the Permaculture Designer's Manual, page 417:

There are several ways to perennialise annuals, some of which are: [...]
Lettuce: pick single leaves, alllow to go to seed, scatter seed.

Last year I forgot to harvest my corn salad seed crop and let is self seed and now my bed is full of a thick layer of corn salad...

I like lettuce better so I was wondering if I could do that with lettuce! I happen to have a variety that already proved that it could self seed and grow volunteers


I am looking for people's experiences, advice, pitfalls, etc so as to how to perennialize lettuce.


Should I seed a bed heavily? or plant a few heads? Should I plant multiple varieties? Any advice/experience?


Other experiences with other crops are welcome too!

Thanks

Technically the description you give about the lettuce makes it a reseeding annual. A "true" perennial means it is growing for multiple years from the same root system. The main practical difference between them in the garden is that the reseeders tend to wander around a bit and the conditions amenable to mature plants, such as heavy mulch, may be inimical to new seedlings coming up. I often find reseeded "volunteers" in my pathways, along edges, and in other out of the way places because of this.
A lot depends on climate and variety. Having gardened in four very different climates (Michigan, Georgia, Bangladesh, and California) I've seen plants that are borderline weedy in one or more of these climates and next to impossible in others. Right now, in CA, I have kale and chard plants going into their third season, which I have never seen before anywhere else.....

ive had naturalized lettuces on a property i cheyenne for 3-4 years now, i started with a simple green leaf lettuce and that has reseeded all over, then over the last year or two ive added a bit of new genetics in so as to maintain diversity and prevent the naturalized lettuce from becoming too bitter as i hear it tends to do left untended, i now have green leaf, red leaf and have had a couple of baby red heads though they tend to turn to leafs as they mature
as for flavor, i dont really get the oppurtunity to eat much of the produce there in cheyenne very often but i believe well be making a salad tomorrow because there is tons of spinach out there as well as some lettuce, kale and dandelions, might even throw some baby dock in the there...