This scope difference is essential:
«لا دائماً»
Not always — denial of permanence of the judgment.
«دائماً لا»
Always not — a permanently negative judgment.
“Zayd does not laugh all the time” means laughter does not continue without interruption. “Zayd never laughs” is much stronger: it negates laughter at every time.
Thus compound modalities require identifying the scope of negation. Denial of permanence must not be silently replaced with permanence of denial.