Day by Day = day after day, aure epe aure

Three by three = three times three, nellume nelde

But three by three doesn't always mean three times. And I just figured it out...neldessen "in threes"

+Tamas Ferencz Nellume? I don't think we can use lúme in such phrases, I believe, it's only about the time (hours, minutes...). It's an anglicism since "a time" has completely other words than "the time" in most languages.

+Andre Polykanine actually this was attested in Early Qenya as a suffix -llume, see eldamo.org - Eldamo : Early Quenya : -llume so if it's an anglicism, it didn't come from me :)

"Day by day" (a Germanic idiom) means "every day" (a much broader idiom). Which we actually have from Tolkien's pen: Q. ilaurea, S. _ ilaurui_.

Day after day
and love turns grey
like the skin of a dying man
night after night
we pretend it's all right
But I have grown older and
you have grown colder and
nothing is very much fun
anymore

sorry, just associations kicked in