Well, I'll tell you what Bass Bug, rather than just weighing the advice of a certified fly fishing instructor against marketing literature from a fly line company, how about we just compare some expert literature on the subject:

Here's an article written by Bruce Richards, world-renowned fly line expert/inventor:
Bruce Richards Article on Fly Line Memory and Stretching

And I just copied this from a Rio Line Brochure that I found on-line: here's the link:

Rio Fly Line Brochure

IMPORTANT
LINE CARE AND USE INFORMATION

The RIO Fly Line you have purchased is the finest line
of its kind. We use special processes to insure the casting
loop stays straight and does not sag when used
in typical, seasonal temperatures. However, all new fly
lines need to be broken in, which usually takes a day or
two of casting and fishing. After you have put a new
line on your reel, run the line all the way out with no
leader attached. Gently, with no pressure applied, start
at the backing and �walk� any coils out to the tip. Do
this about three to six times. When you start to fish and
you�ve put this line on a small arbor reel, or when using
it on a cold day, please pull out the amount of
line you expect to use and give it a slight stretch--slowly--
do not jerk the line (a couple of pounds of pressure
is all that is needed.) You do this to relieve the coils
or �set� the line takes on a small arbor reel, or on a particularly
cold day.

And last but not least, the L. L. Bean Fly Fishing Handbook says:

L. L. Bean Fly Fishing Handbook Line Stretching


If you do it, you will notice an improvement in ease of casting and line handling. It's not so much "a problem" you're avoiding as "an edge" you're gaining.

Stretching your line each time is good practice, but I'll admit I don't always do it. Unless I know I'll making long casts or I'm doing a demo or class, I usually just start casting and stop to stretch the line if I'm having problems with the line. It is usually more improtant to stretch the line in cold weather or cold water than it is when fishing a Texas lake during the summer. If you'll take the time to do it, stretching your line does help.

However, I always stretch/straighten my leaders.

Rex, good advice as always.

If there's ice forming on your carpet or your butt starts sticking to the seats, or you're wearing them fingerless gloves cuz it's only 17 degrees outside, lots of times that shootin line restin on your feet looks like the curly hair of a rag doll and then like Rex I'll straighten it.

Usually though, I'm too lazy, and won't stretch it. Shootin lines like not the kind that's restin on your feet but for head system fly fishin, well, they need stretchin every time or when you go to make that 150' cast they tend to turn to dreadlocks immediately and without the influence of any marijuana, medicinal or no.

Hmmmm... Near as I can remember the last time my line got stretched it were a trout hole that dun er!

I don't see the need to stretch your line in Texas unless it's SW line in the winter (and then maybe you should not use a SW line).

I've laid them out to straighten occasionally, but I've never once had to actually stretch my freshwater lines, even in freezing weather, and they work and shoot just fine. But with SW lines, I can see how it can help, esp. since your usually wanting to shoot a lot of line. Also, seems like RIO lines have more memory than SA lines.

I'm also careful about not letting mine sit in the car in the heat on the reel, which can lead to memory. So the Richards article mentions that the majority of lines are nylon core. Is he talking about mono cores, cause that's a whole different ballgame. While there are a lot more mono cores these days, I thought many if not most lines still had a dacron core, which is made of polyester and has significantly less memory.

The Rio Saltwater Clouser that I use a lot of the time seems to have a lot of coiling when I first strip it off the reel, but after a couple of minutes of fishing it isn't noticeable anymore.

The vast majority of fly lines are constructed with a multifilament nylon core. Bruce would know, he's a fly line designer. I don't even know where you would get a line with a dacron core, they're for extreme distance anyway. Like if you shave your legs to swim faster, you might have a dacron core for casting competitionts. In his book about fly lines Richards says that's because if the core didn't stretch a little, the coating, which will always have to stretch some, would become detached from the core, a bad thing.

That stuff is all kind of minutia, but if you're gonna talk minutia it is important at that level.

Up here in N. Tx those of us that fish year round have some line coiling problems in Jan and Feb from time to time with regular all around lines of various brands. Surface temps on some of our lakes then run about 42 degrees.

Is it minutia season already?

Don't forget you have to buy a stamp to participate in minutia season...


I've given up on trying to get that deep into the details, after all it's just fishing.

Rex

Gotcha. Always assumed it was Dacron.

But when you can't be fishing you can distract yourself from the lack thereof by getting lost in the minutiae.

Or you could just read fishing stories, and tie flies and leaders. All that talk about leader tieing in another post got me experimenting some with the ones I tie. LHD caught my eye with using three sections of equal length. Didn't really like it, but 50% butt, 25% mid, and 25% tippet seems to work pretty good for me. Also played with loop to loop and double uni connections between the sections. Jury's still out on the knots. Wait, I think I'm getting caught up in minutia now.

Anyhow, I stretch my line when it starts acting funny, but can see the advantage of doing it every time.

rod tip down on the water and keep the line straight. I feel the "takes" just like using crappie jigs.. The fly type fishing hook-up ratio is lower for me then conventional gear but I have developed a pretty good sense for how to do it with the fly..