I think perhaps a couple here missed the point of my original post...
This isn't about Intros... This is about what you can do with them if you DON'T use them!
There IS one small, but important difference with Intros rather than Fills for the 'pickup' use of them. For Break/Fill use, you are good to go, but if you try using them for a more subtle 'Fill-to-same' there is something you need to be careful about. Fills will drop into the fill up to 2-3 beats late. In other words, ask for the fill on beat 3, you will get it immediately.
But if you use an Intro for the 'pickup' type fill, you will HAVE to remember to ask for it a bar early! Intros do not start until the END of the bar you ask for them in. A small, but potentially important point!
BTW, perhaps you need a vamp in the middle of a song? Maybe you'd like something like Ketron's 'Riff' feature? Maybe you'd like to jam over a groove and use your LH for the bender, or maybe you'd like to solo on a horn, or guitar, or do some patter as an entertainer...
How about a 16 bar sequence...? Perhaps you have something in an SMF you like, or you could just make an SMF from the style, with changes in them (or vamp on the one chord).
Import this into say Intro4... Now, hit the intro4 button, and off you go! If you want to extend it, remember to hit Intro4 again in Bar16 (if your arranger won't loop Intros, like mine won't!).
There are all kinds of uses for those unused Intros!
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An arranger is just a tool. What matters is what you build with it..!