How fast your charger can charge your cells all depends on the condition of your pack. If each cell has the same voltage during charging then the faster they will finish. The only reason why some packs takes forever to charge is because the charger is spending a significant amount of time at low current charging, trying to balance charge the pack so all cells are at the same voltage.

Balance CURRENT has nothing to do with balance CHARGING. Balance charge basically takes into account the cell voltage and limit the charge current. Say one cell reaches 4.2v and the others are at 4.0v. The charger will start reducing the charge current to prevent the cell from going over 4.2v until all cell is at 4.2v.

Balance current is only used in the balance function, it equalize the unequal voltage of each cell in a pack. Say one of the cells in your pack is at 4V while the others are at 3.85, it essentially discharge the cell that cell until the voltage matches the other cells. The higher the balance current the faster it balances. In your case, the 4010 has 1.2A of discharge current to drain the cells in the pack so each one of them are the same