How are working hours statistics computed? In a recent conversation, I was suggested that national working hours aggregates, as provided by bureaus of statistics, are based on surveys on time use. 

Is that true? Can macro labor data, which is used for so many different puzzles and theories, be vulnerable to things such as time-varying biases in estimating time use? How are national working hour statistics computed?
Referring to USA, the place to go and learn a lot (if not everything) about the matter is The Bureau of Labor Staitstics

Indicatively, for one of BLS's many outputs, they report that:


  Payroll survey — methods and measurement issues
  
  The Current Employment Statistics (CES) program, also known as the
  payroll survey or the establishment survey, is a monthly survey of
  approximately 143,000 businesses and government agencies representing
  approximately 588,000 worksites throughout the United States. From the
  sample, CES produces and publishes employment, hours, and earnings
  estimates for the nation, states, and metropolitan areas at detailed
  industry levels.
  
  The CES employment series are estimates of nonfarm wage and salary
  jobs, not an estimate of employed persons; an individual with two jobs is counted twice by the payroll survey. The CES employment series
  excludes employees in agriculture, private households, and the
  self-employed.
  
  ...The entire sample is redrawn annually, and a supplemental sample of
  new business births is selected midway through the year. About
  one-fourth of the sample is rotated out each year and replaced with
  newly selected businesses.
  
  All new sample is solicited by computer-assisted telephone interview
  (CATI), and data are collected for the first 5 months via this mode.
  After the initiation period, many sample units are transferred to one
  of several less costly reporting methods that are self-initiated by
  the respondent...
  
  Estimation Methodology. 
  CES monthly employment estimates are made using a two-part estimator.
  The sample reports are used to estimate month-to-month employment
  change from continuing businesses and a birth/death model is used to
  account for new firm births that otherwise would not be sampled in a
  timely fashion.
  
  Estimate review.
  CES uses automated edit and screening techniques to identify potentially erroneous sample data; respondents are
  re-contacted as needed to validate or correct their reported
  information. After the microdata edit process is complete, monthly
  estimates are calculated. Automated edits of the estimates are
  supplemented by analysts who look for errors and outliers and provide
  final validation of the series before publication.
  
  Seasonal Adjustment.
  The seasonal adjustment process removes from the series the effects of
  normal variation from recurring events within a year, such as holidays
  and weather changes, and helps reveal underlying economic trends. CES
  uses a concurrent seasonal adjustment methodology, meaning that it
  incorporates estimates up through and including the current month’s
  data to achieve the best possible series.
  
  Monthly Revisions.
   CES first preliminary estimates of employment, hours, and earnings are published each month approximately 3 weeks
  after the reference period. Estimates are then revised twice before
  being held constant until the annual benchmarking process. Second
  preliminary estimates for a given month are published the month
  following the initial release, and final sample-based estimates are
  published 2 months after the initial release.