An added thought?
An answer, surely, is that you would normally grow a hearting lettuce or a loose leaf one. Any of the latter allow you to pick - rather than cut - leaves whenever you wish. Like the Australian Yellow & its friend below. And, of course, 'salad leaves' can, as said, be 'cut again' when young throughout the season.
You certainly can pull an outer leaf off an untidy Iceberg - I did it several times this year with Pablo. But it is not the norm.
The yellow thing got to 40" across!!
Sorry - wrong lettuce see the next one - but you see what I mean?