I have a 90 space system with six Q106 oscillators (12 spaces) and a Dual Waveform Generator (Buchla 258 clone) from Sputnik Audio (2 spaces). So, not counting LFOs, I have 8 oscillators in 14 spaces, using 15.6% of a 90-space system.
However, taking LFOs into account, I also have two SSL Tap Tempo LFOs (2 spaces each) and a Megaohm LFO Two (1 space), so that's another 4 oscillators and 5 spaces for a total of 18 oscillators in 19 spaces (21%).
Then there are the modules which are not oscillators per-se but either can be used as oscillators, can self-oscillate or have a built-in oscillator: I think all of my filters except the Q127 FFB can self oscillate and I have seven (Q107, Q150, Q107A, Delta, 2xCdS and Mankato). I have a Sputnik Dual Function Generator that produces loopable envelopes, the Q157 SH++ has a built-in LFO, my two Ardcores could be programmed to produce LFOs, and even the Q119 Sequencer could be used as a very expensive LFO. But I'm sure that's not what the OP mean and these are resources that are rarely used as oscillators - with one exception, one of my Megaohm CdS is my go-to kick-drum generator.
I think 4 VCOs are ideal for a 44-space system. That's what I had when my system was that big (see pic below) and I squeezed 3 or 4 voices out of it. I very rarely stack more than two oscillators. My modular approach is having multiple voices rather than one single huge-ass sound. But lately I've been interested in drones, so I might just try doing a 6 VCO patch into 3 different filters or something.
