I read a sound on sound review of the prohet 08 and there´s this sentence:
“you’ll never find that the concert-hall-shattering-note you expected comes out as an apologetic squeak because the two oscillators are out of phase with respect to one another”
could this being out of phase of the oscillators be what haunts my friends moog prodigy that on some days just doesn´t produce a good sound?
To put it simply, yes. 
thanks!
care to “put it complex”? 
In “complex”, older analog synthesizers that do not have auto tuning or newer ones, like the Voyager, have a tendency to go out of tune. This is caused by the temperature-sensitive oscillators reacting to certain environments where the temperature changes, or reacting to the heat created by the other components in the synth.
These instruments often require the user to remove the back panel and re-tune the trim pots on the circuit board using a multimeter to get the oscillators just perfect. The Little Phatty has self tuning, so it doesn’t require such TLC. Enough information? 
BTW, I’ve never heard a DSI make a concert-hall shattering sound. I had no idea they were capable of that. Maybe if you turn the filters to max and rest your arm on the keyboard? 
I’m not sure everyone’s talking about the same thing.
One can have two identical oscillators, put one through an inverter and mix them. One osc will be 0 phase, one will be 180.
Regardless, you may not hear much of a difference at all.
Or… one can take two identical oscillators and tune them slightly off from each other. They’ll both in phase waveform-wise, but will beat against each other in a way that’s often coined as “phasing.”
A Moog Prodigy therefore wouldn’t sound any thinner if one oscillator is 180 degrees out of phase and since it can be detuned, shouldn’t have any problem producing the familiar phasing effect either.
It’s probably some other reason the Prodigy sounds weak at times.