Practicing can be broken down into three categories: repertoire, etudes, and fundamentals. A pyramid-style diagram with fundamentals on the bottom, etudes in the middle, and repertoire as the peak, would be appropriate here, if cliché. This is just an application of the idea that more general practice applies more broadly, and that any specific challenge can be disassembled into component parts that can be addressed separately. In other words, efficient and effective practicing.
Here's the difference between the three. Any given passage, let's say the first solo from the Ravel Piano Concerto, has certain specific challenges. This one has been on my mind (and my stand) for the last little while because it's up this week, and especially because I've never felt like I've performed it as well as I could and I especially want to knock it out of the park this time. In this case, the most obvious challenges are articulation in that nasty tempo between single and double tonguing, stability of tempo, and, since many (myself included) choose to play this piece on something other than their main horn, fluency on the D trumpet.
But no matter how much I play through the excerpt, even picking it apart, I'm not going to get the quality of results I could if I tackle those challenges more generally. Most importantly, what progress I would make would be less likely to carry over to other repertoire, because I'd be addressing very specific tasks. Instead, I can approach each of the challenges in a general way, tailoring my approach to areas I need to improve or refresh, and not dwelling on the things I'm already on top of.
Here's a breakdown of the key fundamentals at issue. Of course other are at play as well, but that spider's web reaches into all corners of playing the instrument.
Articulation - I spent a long time trying to speed up my single tongue, but I eventually realized that there's a wall that I'm just not going to be able to break through. Instead I decided to go around it, and I've become a big proponent of mixing Ks into strings of Ts. This was encouraged to me in my studies with Michael Sachs at the Cleveland Institute of Music, and he touches on the idea in his excellent book Daily Fundamentals for Trumpet. Ravel Piano Concerto is a perfect place to apply this. Refreshing my basic fluency in this is practice task number one for me, as it's something that I use extensively in the piece.
Stability of tempo - A very general skill, and one that I find is often tied to technical fluency within a given passage. Of course, the metronome is your friend.
D trumpet - I find that the most effective way for me to be comfortable on a horn is to play it every day. D trumpet doesn't enter the rotation too often, so I start getting in touch with it at least a couple of weeks before serious work needs to start. I find the best way to get used to an instrument is to incorporate it into my warmup. When I need to be ready to perform on C piston trumpet, C rotary trumpet, D trumpet, C cornet, and piccolo trumpet, I'm switching a great deal in my warmup.
To get used to really applying these, especially in combinations, the appropriate tools are etudes. It's important to remember that etudes should be chosen with very specific goals in mind, and if you can't find the right etude you should make it, either by changing one you've got, or writing something yourself. For the Ravel, I've found two Charlier etudes to be very helpful. Number 31, in C on D trumpet, is perfect for applying TTTK or TKTT articulation patterns at the fussy tempo in question, and also has the benefit of reading in the same key as the first movement of the concerto. Number 33 is a good challenge to address many of the complications of the third movement, though the connection is admittedly more tenuous than 31 and the first.
Beyond that, it's just a matter of applying these skills to the original passage. Using techniques of 'skeletonization' and other generally applicable practice ideas, you should find that transferring the general skills you've developed through practicing fundamentals and etudes will give you a more satisfactory product than you would have gotten otherwise.
The most important thing to remember is that if you can’t find an exercise or etude to address what you need, make one for yourself! Either by writing something or altering an existing etude by key, articulation, speed, or anything else, can give you the tools you need to make the most of your practicing.