Personally I deep litter on straw. Saves no end of waste, makes mucking out quicker and I only have to put dry on top once or twice a week. Added bonus of not having to have muck heap removed so often. Started doing this last year, and only used two large rounds between two horses and a pony all winter.
I use rubber mats and dust free shavings on top. Mine live out most of the year come in daily for riding, training, feed etc then out again. In the winter they come in lunch time for feed and hay then go back out at 8pm, only stay in if snow or torrential rain. Saves massively on bedding.
I find woodpellets economical and use these in the winter when the horses are in at night, if you use a decent amount to set the bed up you shouldn't need to put 3 bags a week down. I just take the poo out in the week and then dig the wet out once a week which saves loads of time and I can muck 4 out into one big barrow in the week.
I use rubber matting, all year in work I shred lots of paper and so far have 8 bags (1 bag same as 1.5bales of straw). Once gone I will use straw, 1 bale lasts a week, I only pick out poo through week and do full muck out on weekend
I deep litter on rubber mats with Bliss or one of the substitutes around. Then I just skip out during the week. I use a Equine Speedskip they really help reduce the amount of bedding you can waste with a shaving fork. Once a week brush the dry bedding off the wet (which sinks to the bottom and clumps together) and dig out, then replace wet match with about half a bale or a bit more if you've got a very wet horse. You need to be fairly generous with initial bed for the best long term results.
I deep litter on shavings. Only go through 1 bale per week. Also only use half a bale at a time , keeps the bed fresh and crispy. My bed is quite big though , it had a lot of bales to start with .
We use probed, chopped & treated rapestalks, on top of eva mats. It seems to spread out more per bale than shavings but still gives a springy deep base and the poos don't seem to get meshed about in it like shavings so very little is wasted when skipping out. Also it decomposes as quickly as straw so the muck heap can be taken away by a local farmer.
Straw works out by far the cheapest for me. I have 5 on straw and 2 on shavings/aubiose (sometimes have a problem getting hold of shavings) as they both like to eat copious amounts of straw. I am a little bit in love with aubiose and if I was super rich I'd have them all on that.