Present Simple or Past Simple
Which is more common for native speakers to use in the following construction, present or past?
She is really a good friend and she never 'fails/failed' to send me a letter each month.
The most common combination would be
She is really a good friend and never fails to send me a letter each month.
Reason: it's nice when the two clauses linked by "and" are in the same tense, when the context permits that. It certain does permit it here.