If you are trying to shoot LF with old lenses (and therefore old shutters), you'd have to hope that the shutter behaves the same where you're shooting as it did on the tech's shutter tester.

Having a shutter tester you can take into the field will tell you how far off that 1/30th second setting is, telling you whether you need to adjust aperture to compensate.

I'll also tell you whether the shutter needs a CLA - if you trip the shutter five times and the reading varies by more than a half a stop, then it's hard to predict what exposure you'll actually get when the lens is used to take the exposure. When you see that, it's time to have the shutter serviced.

And no, you do not need any special 'technical knowledge' to do this, or at least, any more technical expertise than it does to operate an LF camera. If it's off by more than a third of a stop, and you're using transparency film, you're gonna get an incorrectly exposed shot and you start to question your sanity and your ability to wate $3.50 per sheet (just for processing!!) on these incorrectly exposed shots. If they're for a client, you might need to do a reshoot.