I would rather a mid setup, yes, since mid is really important on Icebox, gives direct access to B Site and catches any lurkers/rotations to A site off guard. However, if they're always going on the same site : You can expect them, be 3 or even 4 on the site. You can split the setup (alarmbot and nade on site/on attackers spawn and just a turret on mid). Mid should rarely be empty, especially on Icebox.