Hi. Although other protocols exist for more expansive routing, in some cases it's easier to create a group of target addresses and assign a route to the list rather than create a lot of single route rules. Although the backend won't work like this, if it was possible to have it transparent on the GUI or via CLI to auto-generate them it'd help simplify the tasks.

By this I mean using the same methods as firewall filter rules where under Adddress Lists you can specify I.P/ranges and then in the filter rule itself specify a Dst Address List. This way the route table itself is visually small and the address lists can be managed directly.

In our case we have 2 internet connections, one has faster commodity internet whereas the other is primarily a Research & Education network (GLIF). As some are much more efficient over the GLIF with peered partners we would prefer that only selective routes go down this path rather than the other.
We do have a BGP AS for the GLIF connection but not with the commodity internet one unfortunately.

Use BGP policies!

BGP as mentioned or policy routing where you can use already implemented address lists.