I started it about four years ago, doing a few weeks work on it here and there when I wasn't skinning planes. It has been redone umpteen times to address developments in the game like the strat cities, new terrain systems, the 20% capture rule etc.
Also players have suggested improvements which I implemented, particularly Easyscor who found a lot of bugs in it, Fester who suggested revisions to TT and TDeacon who suggested grouping SPs close together at each base and adding the chains of V bases.
I doubt I'll do another unless there is some addition to the game like bridge bases that would create some new tactical dimension to MA terrain design.
The Sea Hurricane was added after I submitted the terrain, so that's an HTC booboo.