In theory. In practice one OST player cannot compete with 4 Allied players in building caches for the team, neither in time, neither in resources available. OST has the highest bleed of all and is usually manpower starved. Unless of course the OST guy doesn't do anything else but building caches while 3 OKW players enjoy 4 vs 3 for a good couple of minutes. It simply does not work that way.
In practice this is how mOST of my 4v4 ostheer games go. I am often with 3 OKW.
I build a few pios and mgs at the start to cover fuel/flanks/cutoffs. After each successful engagement, or after the first retreated pio is reinforced I start building caches where I can.
The idea is to use pio flamethrowers to support okw in clearing garrisons and use mgs to keep them from being overrun by blob concentrations.
After that it's usually brummbar next or t2 for flame ht for simcity and/or pgrens for clearing team weapons.
Point is in 4v4s one player can easily do nothing but support. I'll sometimes FHQ as soviets all along the frontone to create ungodly strong positions for usf ukf allies. That kind of teamwork has more impact on the match than any faction design or individual unit performance.