A problematic condition can occur when the installation of a new static
route affects the resolvability of its own intermediate address.

At first,
the 20.1.0.0/16 route is installed in the routing table and the intermediate
address of 20.2.0.2 is resolved using the default route.
However,
the classful routing table lookup process does not allow a default route to
resolve intermediate addresses. After 60 seconds, the next time the static
route process is scheduled to run, it will remove this route. In another 60
seconds, the static route process will install the static route back into the
routing table, again using the default route to resolve the intermediate
address of 20.2.0.2.
This process of adding and deleting this static
route is repeated every 60 seconds.
Notice the times
in the debug output. This is also a demonstration of how
the static route process is implemented every 60 seconds.
This situation
can create even more instability if there are other static routes resolved by
this route. One solution is to always configure static routes to use exit
interfaces instead of intermediate addresses wherever possible.