With the old Airbus performance manuals it was always an option for a Captain to reduce the Flex temperature if he so desired (yes, there are many good reasons why he might want to do so, and the book outlined the method).
But with the introduction of Flysmart on EFB most operators seem to have removed that option from Captains. They want Max Flex on every takeoff, no matter what the Captain might feel appropriate on a given day.
There is always the solution of going TOGA - but certain of these operators are known to ring up Captains and berate them for using TOGA. So, many invent other methods to avoid confrontation by avoiding using TOGA, but to reduce the Flex temp, and give themselves better margins, which won’t be noticed by management.
Adding tailwinds, doing performance figures from displaced thresholds, reducing runway length, using the wrong intersection - I’ve seen them all done, and I don’t like any of them. It’s fakery, and if anything at all goes wrong you’ll be hauled up to explain where you got your inventive ideas from, andyou will of course be hung out to dry.
The correct way is to go TOGA if you aren’t comfortable. That’s what I did, and I told the FOP Manager that’s what I’d be doing, and not to bother calling me for an explanation. They had left me with no other choice.
I was never harassed, but i know they took a severe dislike to me over it.
This is what our profession has been reduced to by the bean counters. Flying Monkeys, with less and less discretion every year that passes.