for some reason you are talking about formulating feed (mixing dozens of ingredients in correct proportions like feed companies do) and giving your birds no other choice but eating that feed.
The original discussions was about giving the birds free choice access to fruits/veggies instead of considering them harmful and "in moderation as treats only"
I'm talking about formulating feed, because offering treats "free choice" is exactly what you are doing. The equivalent of placing an ice cream bar, a chips and dip tray, and a cooler full of beer in front of a frat boys at the football game, then expecting them to eat a whole-grain starch, some green leafy veg, and a lean protein as a complete meal afterwards.
BYC is littered with people feeding very expensive, "healthy-sounding word"-heavy feeds, then finding their birds have nutrition problems because their hens are picking out favorites in accordance with flock order, and disregarding the rest - to their nutritional detriment. Plenty of poster offering too much scratch, BOSS, meal worms, etc - and they have no reference with which to judge the effects on their birds.
Offering a treat or two, in whatever quantity the birds want does two things.
1) It ensures they will displace part of their complete feed in their diet to eat the desired goody.
2) It ensures the total daily nutrition of the bird will be imbalanced in a way directly related to the nutritional makeup of the treat in question.
Even offering a range of treats is more problematic than not - at best, you are in the same situation as the owner offering those whole grain feeds, their birds playing favorites. At worse, your range of options fails to even offer the balance. Birds can't eat what they aren't given. If your treats are all legumes, you end up with one sort of imbalance. All seeds, you end up with a different sort of imbalance. All grains, yet another sort of imbalance. Read up on "protein complimentation" - there is surprising overlap in the theory of feeding humans and feeding chickens, on that particular subject.
Its part of why I've worked so hard at offering my free-ranging birds a host of options, all times of the year, in their pasture. Grasses, grains, seeds, legumes, forbs. Which I use as a suppliment to a complete feed. and I stick my hands in their guts almost weekly, looking for evidence of dietary problems which might escape external visual inspection.
Since you don't know what you are doing - clearly - the thumb rule is that treats be limited to not more than 10% of the daily diet, by weight, daily. and that treats be rotated periodically. That's to help those who don't care to understand the science from doing damage to their birds in their ignorance. No guarantees of course, the figure is quite conservative - but it fits the majority of situations, and thus has some utility.