It's terribly hard to qualify a speech-only child based upon specific articulation errors because the age range for age of acquisition is so wide. However, for the sake of this discussion, let's set aside the issue of qualification and just discuss treatment. You have a (hypothetical) child enrolled in therapy. You've been treating them for some time, and the only errors they have left are "age appropriate." Do you continue to treat or discharge that client from therapy?
Or, let's say you have a child with a frontal lisp on /s/ production that is very noticeable, but they're only 4-5 years old. Do you treat the lisp? I'm inclined to treat. I feel like letting certain errors go just tends to set them in stone, so to speak. By the time the errors are finally age inappropriate, the mispronounciations are fully habituated and harder to treat than they would have been if you had addressed them earlier.
I was hoping to get some other opinions. Have any of you encountered situations where children with a history of speech errors that need treatment had "age appropriate" errors resolve on their own without treatment as the child ages? I'm prompted to ask because of Michael.
Michael had a tendency to produce a wide variety of sounds interdentally. /f/, /v/, /s/, and /z/ were all produced with significant tongue protrusion. Given his abnormal speech history (almost completely absent babbling, no vowel productions or "cooing" until over 8 months of age, no words at all until 15 months...) and his sister's more significant speech issues, I decided to treat. /s/ and /z/ are pretty much completely resolved, and /f/ and /v/ are well on their way although still problematic in conversation. At 4 1/2, problems with /f/ are now age inappropriate, but that's the only speech error he has that currently would "qualify" for treatment.
I could step back now. I could work gently, but persistently on /f/ and /v/ when they come up naturally in conversation and just take a wait and see approach on the final remaining errors (/f/ for /th-/ and /d/ for /th+/). /th/ is a sound that would never qualify for treatment at 4 1/2. Given the history, would you wait and see if the /th/ resolves on its own or would you work on it?