Yes, it's due to the lead times with printing, distribution etc.
The way it was explained once @ RAPAC was, working back from the maps effective date:
- maps and documents are supposed to be received by pilots and other users at least 28 days in advance of their effective date, so for maps effective on 10 Nov. 2016 that would be receipt around mid October;
- 3 weeks is allowed for national postage and distribution to meet that receipt around mid October, so that process would start around late Sept.
- two weeks is allowed for the mailing house to receive all the maps and documents, collate and send for distribution;
- so the documents would be sent by the printers to the mailing house around mid September;
- the printers have a week or so to do their bit, so that means they receive the data late August;
- Airservices charting people have 4 weeks to process all the changes to the charts, produce drafts for checking then validate and finalse the electronic data for sending to the printers, so that process starts around the end of July;
- mid June is the cut-off for author areas internal and external to Airservices to file changes with their AIS people, which allows for late filing, checking and validation of the data and creating the change documentation covering the whole AIP suite including maps.
Changes e.g. addition of a strip could be done by NOTAM if the level of traffic justifies it, but then the regulator gets involved to assess the safety implications of doing something by NOTAM (and the risk of some pilots not checking NOTAM) vs.. leaving the change till a map release.