Pratchett even says in The Art of Discworld that he has received a number of letters from terminally ill fans in which they hope that Death will resemble the Discworld incarnation (he also says that those particular letters usually cause him to spend some time staring at the wall).
However, in the intermediate dimensions beyond time-space the limitations imposed on energy to put it into a state of oscillating motion are not uniform as they are in our physical universe.
A certain space can be covered by energy moving in either particle or wave form in a certain time assuming a specific velocity virtually anywhere in the time-space universe.