This last winter, I lost 1/23. The previous winter I lost 1/11.
I don't split in the traditional sense, no walk away splits. No splitting for mite control. What I do is raise queens with a strong hive using a queenright cell builder and finisher technique. The cells are then added to mating nucs (queen castles) made of the brood and stores from the dink hives from the last winter that fail to build up sufficiently for spring. These nucs are then allowed to build up naturally (without feed) into five frame nucs and ones that don't successfully queen or don't brood up quickly are merged with better performers. Some nucs are sold, some are used to requeen, and some grown into full size new hives, largely by combination with poorer performers. In my area, I need at least single deep hives and preferably double to survive the summer. Winter can be done in a single if necessary, but I prefer three to five deeps.
Hives that I see are doing well and are likely to produce honey are left alone to do that, usually half or more of the total number of hives. If there is insufficient brood to make the number of mating nucs and queens that I want, I will rob some brood from some of the good hives, sacrificing a substantial proportion of their honey production capability. Some bounce back quite well though.