Define long and short.
Against fighters I find that I will aim with intention of hitting, fire a short burst and if I see a hit then I will follow up with the same firing solution. If I miss then I reposition slightly, fire again and again look for a hit. It sounds like a lot but you can do this all in a second or two. Tap, check, tap, check until you connect and then you fire for a couple of seconds.
If you aren't killing the target in 2-3 seconds then you may not be connecting very well (especially with multi gun fighters like a P-47) and you need to re-aim for better effect.
The exception is bombers where you theoretically can be firing for a longer period of time and hitting frequently as bombers are less able to avoid and more able to take punishment.
That's about technique.
What you may be talking about is if there is anything different done to the damage in terms of game/sim world. So far as I know... no. If you hit then it counts the damage done to the piece that you hit. If you shoot in a short burst and then another short burst you may not hit the same area and therefore would need to do more damage to the target aircraft. A short but continuous stream is better because you're more likely to hit the same area with 2, 3, 4... or more, bullets and more likely to cause that part to fail which in IL-2 land means a fire, or structural detachment, etc.
There's also netcode to think about. You're likely to loose a few bullets every time you shoot. This is especially noticeable with slow firing 37mm cannons (as an example) where sometimes you'll hit with no effect. With a stream you're more likely to have your hits recorded. It may be a small percentage lost but it can happen.
So there's some intersection between technique and netcode to be wary of is basically what I'm saying
(Sorry for the essay)