One one hand you can of course say: "that is what I saw" but on the other hand it's also true that "yes, but it's not because the viewfindersensor/film has that size that I need to respect it."
Then again, like Goethe wrote: "It is in limiting himself that the master shows".

Two to three comes close to the rule of thirds, but the real spots are not at  1/3 and 2/3 horizontal and vertical, but at Phi, meaning 0,618.
When Aegipan started his thread on composition, I thought he was heading the way of dynamic composition, meaning root rectangles. These have ratios of approximately:

root two:    1 x 1,4142
root three: 1 x 1,7321
root four:    1 x 2,000
root five:     1 x 2,2361

root two is used in the DIN A norm ( A3= 29,7 x 42 , A4= 21x29,7)

the Phi rectangle (Golden Section) is 1 x 1,618, or 0,618 x 1

remarkable is that the root five equals 0,618 + 1,618.
Five is also a number that is connected to life (starfish, five extremities,...) and the word quintessence is also based on it (quint means five).

This is an endless subject...

To answer the question: I try to make my composition in the viewfinder, yes. But when it looks better at another ratio, I follow my aesthetic sense, not the law.

There are no Borg. All resistance is fertile.