Can I shorten bean soaking time if they'll be slow cooked? I'm making something using butter beans (fasiola gigandes) which will be cooked for a long time (12+ hours) in a casserole dish with liquid covering them.
Normally I would soak the beans first for a long time before discarding the water and using them. Can I reduce/skip the soaking stage given that they will be soaking and cooking in the oven for a long time?
I use a slow cooker almost every time I cook dried beans, and I don't recommend cutting down on soaking.  I typically soak overnight (with a little bicarbonate of soda), and start cooking in the morning, so 10-12 hours soaking + 8-12 hours cooking, avoiding adding (much) acid/salt until towards the end.
It's possible your beans soften more easily than mine,  but with a much shorter soak (say 4 hours, and 10 hours cooking, because I forgot to soak them overnight) I've found several types to be barely edible - I ended up cooking down my chilli , blending it, and eating it as bean burgers.