Isak did just that this past preseason as negotiations with Newcastle United over a fee for the Swede proved difficult.
Eventually the two clubs reached terms worth £125m and Slot said on Friday: "It is not necessary at our club because we also trade players.
"If a player wants to leave and we get the right money for him then this club has shown for so many years now that we then do sell. At this club it is not necessary at all to go on strike. I think it will have the opposite effect.
"You can keep on training here and Harvey Elliott gets his transfer (to Aston Villa), Tyler Morton gets his transfer (to Lyon). There were maybe eight-nine-10 players in the last window who just conducted themselves in the best possible way and we are a club that is trading so maybe write this down for every agent that has a player here: it is not necessary.
"If the right price is paid by the right club for the right player then this club has shown we always do sell because we need this to get our players in. That is different. That is a very positive thing at this club: you get your transfer if everyone is happy."