Well - on a pump the Bolus Wizard takes care of Insulin on Board - we were only discussing this on another thread the other day - I have absolutely no idea whatsoever how to calculate that in, because fast-acting doesn't release itself in a flat curve - during its working time, it rises to a peak and then tails off, so I would have no REAL idea where on the curve of that graph of the last jab, I was at any given time thereafter.
But Miladdo also used to use 3 insulins - a normal long acting and fast acting, with the addition of Humulin S which is a longer-acting 'fast' one ...... you have got to understand A Lot to combine eg Novorpaid and Hum S successfully. (I couldn't even combine Hum S with Hum I without losing hypo awareness and crashing me car - so I would have nightmares if that was the only insulin in the world.) (probably just shoot meself and get it over with)
Some people still like only 2 jabs a day though, and we respect them, it's their decision anyway. So if someone else wants to have 12 that's also 100% fine by me. Come to that - I don't object to other people dogging if that's what floats their boat - just as long as they don't expect me to join in!