Is there ever an instance when flooding coolant can become counter productive when machining a part? Our shop uses mainly Steel, Stainless and Aluminum and
sometimes Delrin. Any thoughts?

depends on the material, insert and coating. turning steels with a tialn coated insert and coolant can introduce thermal fracturing of the coating.
kind of like throwing boiling water on a block of ice.

I dont use coolant during interrupted cuts. But always use it for non interrupted cuts. 347 ss, 321 ss, inco, Ti, We use Tialn coated inserts 95% of the time.

I've never used coolant when using ceramics while turning case hardened chrome.
The heat is required for the ceramic insert to cut.