I've made many items from bookcases to wardrobes out of contiboard and always screwed the corners then covered the screw heads with caps of the right colour.
After finding that the drilling and screwing was seldom accurate I made a jig to cover up to 36" wide boards with holes at 3" intervals starting 1½" from the edges.
The jig had changeable drill bushes, one for the clearance hole and the other 8mm for fitting chipboard plugs that plasplugs made.
They stopped making the plugs over 10 years ago.
I was lucky because I bought up all the stock in the area when I first found the chipboard plugs difficult to find.
I haven't run out YET but will probably use 8mm pine doweling with a pilot hole down the middle to do the same thing.
I timed it all wrong.
If I had made that jig a few years earlier I may have been able to patent it then sell the design to plasplugs so they would continue to make the plugs it was designed to use.
It was made to drill corner joints from either side, in the middle of the 15mm edges and accross the middle of boards for shelving.
That jig made from hardwood, dowels and 2 screws is as accurate today as when made in 1988.