As usual, you don’t know what the heck you’re talking about.
In the Tridentine Mass, six candles are lit at Solemn High Mass, four or six at High Mass, and only two at Low Mass.
At a Pontifical Low Mass, four candles are lit.
During Exposition and/or Benediction,
twelve candles are lit.
The only time a seventh candle is used is at a Pontifical Solemn High Mass (although there are some exceptions, like a
Requiem Mass, in which ase there is no seventh candle).
In the
Missa Normtiva, there is no requirement as to how many candles must be lit at Mass, except that there should be at least two lit.
In keeping with the spirit of post-Vatican II liturgical abomination–I mean, reform!–different parishes do different things, whatever the priest or “liturgical minister” (usually a habitless, man-eating, feminazi nun) wants to do.