I don't head cement unless I need a shiny head for streamers and such. A 5 turn whip finish is all I use.

I learned this from a professional Montana fly tyer and guide. If one of his flies unraveled due to a lack of head cement, he gave the customer a dozen of the same pattern. He told me no customer ever asked for that dozen flies; and as a pro tyer, every step saved meant more flies tied. He figured he saved enough time over his tying career to tied many dozens of flies more by not using head cement.

So I agree with Byron that head cement is not needed when you whip finish a fly rather than use half hitches.