Say you I'd like to have four oscillators that can play at the same time, in order to keep them in tune over time and over different octaves they require an active buffered multiple correct? Or at what point do they require a multiple to stay in tune? Maybe I'm confused

It varies from VCO to VCO. Some are very good about having a very low voltage drop due to the exponential converter. Others, not so much so. But four VCOs does start to get you into the zone where having a buffered mult to divide your VCO CVs is a wise idea. Better safe than sorry, if tuning is critical.