Steve
Mostly Harmless
I call that the "hug, slap, hug" method, and I think it's a pretty terrible technique. It muddies the waters. Either the recipient of the feedback never hears the constructive feedback because it's so well hidden between praise, or they learn to distrust your praise waiting for the shoe to drop. When someone is doing something you want them to keep doing, just give the positive feedback and stop. If they are doing something you want them to stop doing, give them the constructive feedback and stop.In our instructor training, we are taught to do it as praise-correct-praise. Find something positive to say about what they did. Show them one thing they can do to improve it. Praise them when they do that thing.
At the very least, make sure you finish with the takeaway. So, if you want to start with a bit of fluffing, "Nice job, overall, Bob. You have a lot of enthusiasm." Finish with some specific positive or negative takeaway. "I notice you are doing X. Focus instead on doing Y." Or, "I can see that you're really focusing on doing Y. Nice job."