In my neck of the woods czech nymphing as you describe it with more than one fly is illegal. One hook only rule is in effect.
I sometimes Stillwater fish using one weighted chronomid suspended about 4 or 5 feet from the rod tip hanging below my anchored boat. Strikes are usually almost always visible and are often violent. You have to pay strict attention or risk losing a fly rod overboard. Sort of czech nymphing lite.