Doesn’t matter that the WC is going to be played in different conditions, any match preparation under real pressure situations has to be taken advantage of.
You say yourself those players are not too tired, As for modern sports science some of it is absolute rubbish ! there’s no point whatsoever wrapping players up in cotton wool to try and keep them fit if they’re already fit and not tired etc, no logic in it, players can just as easy get a bad injury while practising.
The way cricket is played the fact is batting teams do spend a quite a bit of time sitting on their arses in the stands, maybe sports science can make it easier by supplying them with lazy-boy chairs ? only trouble is someone would have to wake a player up when it’s their turn to bat.