its an excuse from salty fukkbois
Before major, if you see team who is playing on major, playing some random online tournament, you see they are doing some simple things, for example VP on mirage, just pushing B with flashes and smokes on T side. Or doing double push mid as CT.
On major, you see some new smokes, some new pushes that were never seen. So I guess they save something up.
Been the case for over a decade. And not just in CS. Quake players and teams would also save tactics and strats for WSVG/CPL/Quakecon events, too.
It probably happens.
In online stuff they will be playing with their old stuff and in practice with some new stuff.
Unless its something radical its usually only one smoke change or a couple of flashes extra and it makes the difference
the olofpass boost was saved for 6 months or so
Just look at VP. they always push solo for aim duels in ESEA matches. In important match in faceit vs. TSM they used real coordinated tactics for a dew rounds to secure the win.