Comment by simonh

That's perfectly legit and if that works for you fine, but there are automatic ways to mitigate this. If you go into Settings -> Messages -> Keep Messages you can set the retention period for messages to 30 days and they'll automatically get cleaned up.

Of course there may be some histories you want to keep longer than that. Alternatively you can got into Settings -> General -> Storage _> Messages and delete just the large media files directly without affecting chat texts. None of which excuses the issues of course.