A good friend of mine interviewed with me and when he showed up to his interview he had 3 years worth of flying at ATA not logged in his logbook. He just had the printout from the company was was trying to catch up. LOL In the interview thay asked him why he didn't keep it updated. His response was " I never thought I would be going to another interview. Besides, without it I still have 12,000 hours Jet PIC 5000 hours Heavy Jet PIC and if it comes down to someone having more time than me so be it."
I normally filled mine out once a month. I have let it go as far back as 4 though.