[the local angler]

hey all i was wondering recently i tied a bunch of flies for the next few trips and used the spools of thread in the fly fishing section of the store. even using the cement glue for fly tying i found the flies keep coming apart even after a few whip finisher knots. has anyone tried using just regular sewing thread? i am thinking of this and was wondering what the big difference other than some of the actual fly tying stuff is labeled like a wax type thread. specifically i was tying my version of chrono's and i even covered the whole fly with cement figuring it would make the fly last alot longer. i'm not whipping the fly when casting or snagging tree's or bushes during casting but catching alot of fish. is this just a normal wear and tear thing? i fished for like 6hours and caught like 16 fish all in the 4-7lb range. went through 7 flies.