I've got quite a bit of Worldworks terrain myself, it's great stuff.
As for time requirements, it varies. If you check out some of those links you will see ground tiles, and buildings (or other structures). Ground tiles are 7x7" and are typically mounted to foamcore panels. For best result (so you don't get little white foam bits showing through) most go for black foamcore. You can fit 8 tiles on your standard 20"x30" foamcore panel. I buy my foamcore in two-packs.
So time-wise, print 16 ground tiles, trim them, then spray adhesive onto the foam, and carefully fit 8 per sheet. That probably only takes an hour. Then the next day, when everything is totally dry, you need to cut the ground tiles. Working carefully with a steel ruler and sharp knife, that could take another hour. So 16 ground tiles, two one-hour sessions.
For buildings, it's not "difficult" work normally. It's some careful trimming, folding, and gluing. Some buildings have complete interiors, and those will certainly take more time. Others are just "shells" and they take less time for sure. Building a shell building might take 30-45 minutes each, if you take your time, and do it in stages (sometimes you do an initial gluing, and then you need to wait for a few hours before coming back and doing the next step). Buildings with interiors might take an hour or more, because of the extra stuff involved. And if you want to build the internal "bits" for the building (perhaps tables and chairs or book cases or whatever) those little bits are extra time.
I rather look at it this way. I could buy a building suitable for gaming with 28mm figures and have a raw bit of resin. That needs to be cleaned and dried, primered, basecoated, washed to bring out the details, and then probably drybrushed. All for the basic textures. Then there are doors and window sills and roofs that probably get different colors. ANd there may be a few details to pick out (some bricks showing through plaster parts, that sort of thing. How long would it take to do all of that?
Now, print out a beautifully rendered building, trim, fold, and glue. Even if it's the same amount of time (it won't be, the cardstock building will take less time) the end result is a way better looking building. For the price of one resin building, you ahve an entire set of buildings, and you can print and make as many as you want.
Yeah, they are cardstock, and you need to treat them with a little more care since they can get crushed. But then, drop one on the floor and it won't be damaged. Try that with a resin.
Steve