i was wondering if i had to use a new flyfishing leader every time i tie a new fly on?

i got a new fly rod with every thing i need to fish with on thei, i tied a good nail knot connecting the leader to the line (and it wasen’t easy) and the fly to the leader. what i dont know is do i have to tie a new leader to the line every time i want to change a fly?

NO!!! Tie a 2 or 3 foot tippet onto the end of the leader, then tie the fly onto the tippet. Tippet comes in spools rated by diameter. When the tippet frays or you keep changing flies, you just have to retie a new tippet.

Setting Up a Fly Fishing Reel : Fly Fishing Needle Knot for Leader