If you almost always get caught, I don't think that you can call yourself "good". If you were sleeving well, you wouldn't get caught.
Sleeving is one of the most useful concepts in conjuring, assuming you can get rid of audience preconceptions about it, or frame your presentational style so that they don't even consider that sleight of hand is involved.
Even if they don't see it they will still say it went up your sleeve? That is one of the oldest concepts in magic that almost everyone knows.
I used to be in sales and found that a lot of the same principles for sales will also work for magic. One of the most powerful lessons that I learned and I use all the time in my performances is that a problem is only a problem if you haven't resolved it. And the best time to resolve a problem is right at the beginning. For example, if people are calling you out on "it is in your sleeve" open up with a trick that doesn't involve the sleeves, while calling attention to them. State clearly, "A lot of people think that I use my sleeves to control such and such" at which point you will roll up your sleeves partially so that they will fall down to their natural position after you are done with that effect. By pulling their attention like that, they will think that your sleeves are rolled up the entire time. It is something that will take practice, but I garentee that after a couple of tries you will have it fit for you.
Man honestly, I hate sleeving. I know it can be a helluva tool, but I hate it.
Seriously, yesterday I was performing and was wearing my Letter Jacket (The sleeves are tight around my wrist). I did a snap change to change a card to their card, and a guy seriously swore that I sleeved the other card and made me show him my sleeves
I've been doing magic since 1964 and while I've encountered a handful of effects that used sleeving methods, most of them were dated and required one to wear a very loose sleeve design in your coat. Secondly, you're speaking of hours of practice (daily) spead over some rather long months of time in order to become proficient at it... again, a negative in my book.
So the answer is relatively simple to my mind; if you like the method and are willing to invest the time into developing it as a skill, then it is up to you to make it "important" to YOUR OWN WORK... I've not found a need in the course of the past 47ish years, to cultivate it... then again, I've watched guys that were solid with it and working a topit that made my jaws drop... just as what I do grabbed their attention... just for different reasons.
If you want a technique to become a stable or signature for yourself, then work on it and develope it. Understand however, there are few "carved in stone" rules in magic/mentalism when it comes to this kind of supportive technique. Where the more concrete rules are pushed, it is wise to listen-up. But when a skill is "elective"... that is when you gain the opportunity to shine just a bit brighter, provided you do the work that is required for perfecting it... which brings us back to what I said originally; sleeving requires a lot of personal investment and consideration, so you need to ask yourself if this is a skill you are willing to invest in, why and what your ultimate benefit is going to be at the end of the day.
Most of the guys I know that bust their hump learning this sort of thing do it as a kind of personal challenge; they don't like being limited or dependent on how they do things... it's a matter of boredom and puzzle fixing, I guess.
I'd listen to this advice orig poster. I've spent a lot of time on sleeving and contrary to popular thoughts, when done correctly, the sleeve is the last place they'd think it's gone.