Like Ultravanilasmurf,
I tend to plod away at scenery whilst watching television. Tree's and Hedge rows I buy premade .Last Valley is a goto for trees and hedge rows.Although I do end up tweaking up the bases as the colour palette isn't to my taste. As a gamer a company like this is definitely cheaper than doing it your self.
But in general terms my terrain is an uneven mix of totally scratch built for fantasy ( Still trying to finish my castle) .A mix of scratch and heavily tweaked for my 20th century table. My ancients it's a little different All commercial castings but.... I made the masters so you could argue I'd scratch built them.
It's not snobbery or ego simply the castings were free.
Apparently my kid's are getting me some battle field in a box stuff for my Pulp games. As they're sick of getting me paint brushes for Christmas.
They don't understand how anyone can be enthusiastic about new brushes.
I'm of the opinion that there's a great deal of satisfaction in building everything on a table.That said I do find It's also equally nice to every now and then to treat yourself to something thought up and built by someone else.