The truss rod is a simple device that basically has one purpose: to counter the pull of the strings. That’s it. It isn’t meant to adjust the height of your strings; you can’t set your intonation with it; and with a little foresight, you aren’t going to render your guitar useless by attempting to adjust it.
When you bring your guitar into my shop for a setup, the truss rod is adjusted once your new strings have been strung up to pitch. Some necks require a “settling in” period after adjustment and are left as long as required.
Every guitar is different but typically your truss rod will need adjustment when changing tuning or string gauge, or after any seasonal changes, for example from winter to spring, summer to fall, etc. Any time your guitar gets buzzy after it’s been properly setup (for a certain tuning and string gauge) it is likely due to the neck needing a re-adjustment. Just bring it by the shop or attempt it yourself using The Setup Guide. Chances are a quarter turn one way or the other will correct the problem. Considering that Alberta has a very erratic climate, it is likely your truss rod may need more routine adjustments than in other localities.
Quite often guitar necks shift from too much to too little relief (aka neck bow). Too often it is blamed on the last person that adjusted the guitar’s truss rod. I’m not suggesting it was or wasn’t- but this actually happens mainly from a change in the relative humidity of the climate the instrument’s exposed to. This kind of change can happen within as short as a day. What this means is, if you pickup your guitar from a tech, where it plays beautifully – and then a month (or day or week) later it plays awful – it’s a good indication that the neck has shifted. It does not necessary mean the tech did a bad job, or he/she ruined your guitar. I have always offered complimentary truss rod adjustments – it takes no time at all.