I did a few searches and read through the threads I found that seemed relevant. I'd still like a little direct advice from some of the seasoned guys here.
I started playing when I was 8. I never had a problem with air leaking from the corners until somewhere later in college. After college I have managed to play as often as possible in groups... sometimes being a couple of years between anything that was consistent. Practice during the "down" time has been sproadic... usually getting back into decent shape for a wedding, or church gig, or paid pit orchestra or whatever. But the leaking has been there since mid-late college.
Here's the kicker. My tone seems to be at its best when I have a little leakage, or at least when there is the threat of a little leakage. I know that as I developed as a player the leakage slowly crept in there. Maybe it had something to do with wanting to play high more often in college... who knows. Now I'm mid 30's, and am starting to play a little more, and thought now would be a good time to ask about this.
My embouchure currently has my corners pulled back to the sides a bit... kind of like pulling a string tight, but in this case my lips. I pull them back a bit, set them firm, and then let my lips be as loose or as rigid as I need for the range. My corners stay set and firm throuought the duration of my playing, from upper register to pedals.
But I don't "pucker" which seems to solve the leaking problems. It also hurts my tone. I don't know what it does for endurance or range, as I won't stay with a "pucker" long enough to find out due to the tone problems. I read about the "pencil" trick/training, and don't seem to have any problem keeping one horizontal for 10 minutes, at which point I was bored. A heavier pen was comfortable for a minute or two, not sure how long I could keep that up.
Questions... should I worry about the leaking? I don't generally play mic'd. But it does annoy me when it becomes more of a spitty buzz after a really long practice session or performance. If I need to fix it, should I work on "puckering" or is there some advise you may have that can help but still leave my corners pulled back a bit? If the pencil trick is a good training exercise, what length of time should I aim for?