What is the best program to plan multi drop routes?

maybe a professional solution, for trucking companies;

if at all, only against $$$

your best bet is to get a higher end sat nav, enter every morning all the destinations of the day & once you are done, go to the one you can reach the fastest; once there, see which of the remaining destinations can be reached the fastest & go there.

with a high-end sat nav you usually have at least a dozen most recent destination stored in memory, so it takes away the hazle of having to enter them all every time. you merely need a block & pen and at every destination write down the times to each remaining destination to pick your choice.

i have a quite high-end sat nav (TomTom GO 950 Live) but it can't calculate an itinerary of more then one destination with a single way-point.

I've always found greenflag best for this kind of journey, but you can put all the postcodes into tom-tom and it will tell you the closest each time and go to each as a separate journey

Use a good quality sat nav and put in all your drops. It should give you the best route.