Be advised routing rules are useful for FORCING some source addresses or subnet OUT a specific WAN.
a. one has to ensure that they identify if local traffic is also required, as FORCING means all traffic. ( there are ways to deal with this )
b. mangling rules SUPERCEDE routing rules if there is overlap.
c. WHAT determines if the identified sources are LOCKED to the special table or not is the ACTION command.
action=lookup means the router will look for alternate routes on the main table if the table identified in the routing rule is not available.
action=lookup-only-in-table means that if the special table is not available, then no traffic will pass as the router will not look for an alternate route.