Ive seen one of them up in london but round here they are normally 4,6 or 8m.unless its a straight pour into a footing I nearly always use a volumetric these days as its less of a rush,they're so much cleaner as you dont end up with a prick of a drive overload ling barrows because they wanna be off in 5mins.A lot of our jobs we do on gas sites we still do a lot of knocking up by hand though as sometimes it too much agro to keep getting permits for lorries to keep coming on site.