It has been my experience that logbooks are really important to low timers. If interviewing for a job, letters from previous employers seem more important. If you have been flying for an airline a good rule of thumb is about 5-600 hrs a year. More than that is suspect, The exception is charter, or commuter, then you might expect higher. Logbooks are usually not so reLIEable, sad really, they are a kinda diary to reflect upon in years to come.
My advice is save copies of base or sim checks, route checks, ect. They are a good backup. As for me, I had no trouble getting someone to sign off my shuttle flights, or moon landings.