In discussion groups, I will often see people wondering why they can’t find their ancestors’ records in WieWasWie (WhoWasWho). WieWasWie is the largest website with genealogical sources in the Netherlands, a collaboration between dozens of repositories throughout the country. It has over 100 million references to people in the database, but is far from complete.
Each repository has its own schedule on how they enter information. They all started with the marriages and most continued with the deaths and then went on with the birth records. They only publish public records; access to recent records is restricted.
The page What’s in WhoWasWho contains a link to an Excel-sheet or PDF that catalogs the current contents. Here, you can quickly see if the period and town you are looking for is included in the database.