Multiple shuttles increase the possibility of errors. At least for me. It is that simple. So I borrow some tricks from others and invent some of my own to help.
Warning: threat of boredom and desire for a nap for anyone continuing to read.
If one of the shuttles is a tabby shuttle I use a different kind of a shuttle. If I am using end-feed shuttles, for example, the tabby weft gets put on a regular shuttle. Also, if it is possible (it isn't always), I place the tabby shuttle on the fabric at the front beam rather than at my side with the other shuttle(s).
In my current sampling, however, all shuttles are carrying pattern weft. To help alleviate confusion when putting down one shuttle and picking up another I use positioning order.
When I use three colors across the treadles, as I have been doing, the shuttles get laid out at my side in the order that I need them. I place the just used shuttle at the end farthest from my body, and pick up the shuttle closest to my body. After throwing the shuttle I have just picked up, I then place that shuttle at the far end. What had been the middle shuttle is now the shuttle closest to my body, so I pick that up next. This takes practice but it is not too hard to get used to. I still have to watch carefully so that I do things correctly.
If I add a fourth shuttle to the mix I try to use the top of fabric for a resting place, much like I do with tabby shuttles. For example, if I might be using a cherry red for treadle 2 and a violet for treadle 5. Normally (at least the way I have set things up), I would be using the same color for treadle 2 and treadle 5. But now, when I get to treadle 5 I will have to not pick up the cherry red shuttle but rather the violet shuttle.
To help with this new change of plans, I place the two shuttles in question on top of the woven web. And I place those in the order I need them. If I am going to weave the cherry red on treadle 2 and the violet on treadle 5, I will put the cherry red in the front, closest to me. That is the first shuttle I will pick up.
So I weave treadle 1 with the shuttle closest to my side and then place it on my other side but farthest from me. With treadle 2 I will need one of the shuttles sitting on top of the fabric. I take the one closest to me, throw it and then place it back on the fabric, but behind the other shuttle. For treadle 3 I will pick up the shuttle closest to my side, throw it, place it on the othr side of me, on my far side. With treadle 4 I will pick up the shuttle now closest to my side, With treadle 5 I will pick up the shuttle closest to me on the fabric (remember, when I was done with the first shuttle there, I rested it behind the other shuttle on the web), and with treadle 6 I will pick up the shuttle closest to me at my side. Everyt ime I pick a shuttle and throw it, I will place it either to my other side, away from my body, or on top of the fabric, away from my body.
That all takes a bit of getting used to, especially when I change the order. Then I have to remember that the shuttles on top go either first and fourth or third and sixth, depending on what I have decided to do,
And then I got a bit insane. Not that this hasn't all been a bit insane..........
I tried two sets of two different shuttles. Yup, 5 shuttles. I kept one set on the top the fabric. The other set I kept always as far away from me as possible, in the well of my bench. There is a well on each side. The solitary shuttle I kept on the bench next to me. This system does work. But I also concentrate very very hard. And if there is lots of opportunity for making errors with three, there is plenty more with five. I definitely would ot weave for more than 30-45 minutes at a time and I would not weave when I was the slightest bit tired. This is fun weaving but it is definitely not relaxing weaving.