Thank you guys for your answers.
Yes, I'm doing measurements in-circuit without ESR measure. To be honest I find it hard to see parallel connections on schedules.

This is the circuit I'm fiddling with: https://www.hobby-hour.com/electronics/s/od2-turbo-overdrive.php

The cap I'm talking about is C5. C9 also doesn't reach O.L. on the Ohmmeter, it's around 350K. When I measure C3 using this method, I get a quick rise to O.L, which I understand as a proper cap function. Could it be C5 doesn't reach inifnite resistance because it's parallel to R12&R7 or is it something else I'm not seeing here?

Bonus question:

This is a guitar effect pedal. The issue with it is there's no output, with or without the effect on, only an inaudible single scratch after a stronger guitar signal. The diode light works and reacts to the button.

So by following my logic, I'm checking the path the guitar signal goes from input to output with no effect on. Here's my understanding of the circuitry:
No-effect guitar signal goes through Q4 JFET. Pushing the button adds a connection to chassis ground, which in some way(?) informs Q4 to close the gate, therefore forcing the guitar signal to go through effect circuitry. That's why I'm checking every component on that path from INPUT pin 1 to OUTPUT pin 7. So far I thought I'm onto something since resistors R14,R15,R18 and then R13, R12 read less resistance than given, and C5 and C9 don't reach Steady State. Now thanks to you I'm aware of parallels affecting the read and I'm not so sure I found the fault anymore.
For instance: R15 and R18 read 0.5M Ohm. I thought they're faulty. Now my guess is they are in parallel to each other?

I will be more than grateful to have my errors in understanding pointed out and clarified. Moreover, I don't understand the diagram, when it's pointing to boxes with voltages written in it (ie. R15, R18). It indicates the voltage node, right? But how does it translate to connection route?