Hi William,
As Rene has mentioned in the lesson, Cisco by default has Bandwidth and delay enabled while load and reliability are disabled as they change dynamically and Cisco recommended us to not enable them.
So in other term, Cisco wanted to say keep BW and delay only active. In the real world, I don’t see any reason to disable BW & delay. In case you want to disable any of them then it is better to disable the delay and keep the bandwidth enabled because the delay is calculated based on the sum of delays in the path as per the below formula’s
Metric = bandwidth (slowest link) + delay (sum of delays)
Here a good lesson explaining EIGRP K Values for more information.
Hope I could answer your question