I also think nail growth is pretty constant with proper nutrition, otherwise you'd get horizontal growth lines. The only time that my nails stopped growing was after a trip to the tropics. Probably either the strong sun or altered diet were to blame. Oh, another time was with wrong shoes: I thought I could walk them in, but ended up throwing them away.
It's well known that people who walk a lot can get nail problems, that's why the suggestion to take extra care in this time.