Hi Jeff
Doesn't take that long as I've built a Woodland dio terrain 4'X4' alongside the Civil War terrain. The self built trees are positioned either as singles or in groups on grass flocked resin bases making it quite easy to completely change the look of the forest for each seperate scene or episode and then scattering forest litter/bushes/foliage/earth/rocks and grass to cover the joins and also the bases of the figures to give them a little more authenticity of standing on their feet rather than standing on an ugly metal base.
That's one thing I've learn ed from just collecting toy soldiers to then displaying them in dios is to always try and disguise the figures base stands. Now in a forest or field or rubble or desert terrain that's quite easy by using any of the above, not so easy when you want to do a "parade" type dio especially if the figures all have different colored bases. Dont know what that's got to do with your question but I've added it anyway
Thanks for your comments
Reb