We run quite a large multi-site Cisco network using EIGRP as the routing protocol. Many of the sites have a backup link but looking at the topology table there are virtually none that have a feasible successor. This seems to defeat the object a little of running EIGRP, because of instead of immediately switching to the backup route it has to recalculate. It ends up using the backup route eventually anyway!
I know that EIGRP must be doing this because of its AD versus FD calculation to avoid routing loops, but as it eventually uses the backup route it means that it could have used it immediately.
Is it advisable or best practices to alter the delay or bandwidth of links where there is a backup link so that a feasible successor gets put in the topology table? I'm pretty sure that whatever alterations are put into these fields can't result in a routing loop due to EIGRP's calculations (well I'm not 100% sure but I tried it in a home lab and it seemed to be fine).
Can somebody advise me on the best practices please? After all there's no point in running a supposedly very fast converging routing protocol if it never actually inserts any feasible successors into its topology table and so ends up not being particularly fast.