I know that, in some cases, it can change the meaning. For instance,
"The delay depends on how the cpu handles the processes and the network load."
is ambiguous and could mean that the cpu handles the network load, while
"The delay depends on how the cpu handles the processes and on the network load."
is more clear.
But, what about:
"The travel time depends on how fast you walk and the distance to your destination."
There is no ambiguity here, but would it be better to put an "on" preposition before "the distance to your destination"?