If he washes his right foot and dries it then he washes his left foot, is continuity interrupted?

Continuity in wudoo’ means not delaying washing one part
until the one before it has dried within a moderate amount of time, such as
if the part dries because of intense heat or a breeze or by being dried with
a towel, for example, if the time taken for drying it does not take too
long; what matters is that it should not take too much time. 

Some of the scholars describe continuity as meaning that
there should not be too much time, as defined by custom, between the washing
of various parts of the body, and that is not limited to the time it takes
to dry them. 

Ibn Qudaamah said in al-Mughni (1/181): The continuity
that is required is that one should not leave washing another part of the
body until enough time has elapsed for the previous part to dry within a
moderate amount of time, because a part may dry quickly at some times and
not others. End quote. 

It says in Kashf al-Qinaa’ (1/105): Continuity means
that one does not delay washing one part until after the part before it has
dried at a time when it is neither too hot nor too cold. So one does not
delay washing the hands until the face has dried, or delay wiping the head
until the hands have dried, or washing the feet until the head has died if
it is washed. From this it may be known that if a person delays wiping the
head until his face has dried but not his hands, that does not matter. End
quote. 

Based on this, if a person washes his right foot then dries
it, then he washes his left foot without taking as much time as it would
ordinarily take for it to dry by itself, then his wudoo’ is valid. 

And Allaah knows best.