The strings dragging through the nut actually file the slots and over time you will notice a bit of wear. When you change strings, you can put a drop of silicon oil on the nut and wipe it into the nut slots with your finger. A little bit of oil can help keep the strings from binding and prolong the nuts' life. About once a year (of average use) you will want your local luthier to touch up your nut with a nut file.

The fret wear varies drastically with the individual. I've seen guitars ten years old with perfect frets and some a few months old in need of a dressing. Just watch for wear. If they are a little worn you can get by with polishing the frets or a fret dressing which simply files out the wear and recrowns the frets. A fret dressing usually is about half the cost of a fret job. A fret job is worthwhile when the frets are so badly worn that there is not enough height for a reasonable recrown. Usually a guitar needs a fret job in five to ten years of average use.

The fingerboard and bridge are finished with an oil and wax finish. About every six months it is a good idea to polish and clean the fingerboard with a fine 'Scotch Brite' pad (or fine steel wool) then wipe a little lemon oil (or boiled linseed oil) on the fingerboard and bridge to help keep them from drying out. A few drops will do the job.

The truss rod is not an action adjuster. Its sole purpose in life is to counter the strings' tension. The truss rod needs adjusting with major climate changes or if you change your string gauge. And how often it needs adjusting varies with your area's climate and the individual instrument's neck. Usually a six month to one year interval is plenty or as buzzes appear.

The saddle is adjustable by fitting little hardwood shims under it to raise the string's height or by removing shims or saddle material to lower the height. I do not suggest more than two shims (approximately 1/32" each. 1/32" at the saddle raises the string action at the 12th fret 1/64"). If it needs more than that it is time for a new saddle. The height of your guitar top raises and lowers annually with heat and humidity changes. If the strings rattle or the action feels a little high, it's time for an adjustment. Again this varies greatly with different areas. Your guitar might need a tune up every season change or it might never need one. Natural aging of an instrument involves the neck settling into the body and the top raising a bit. So annually it is a good idea to have your local luthier check your action. That is a good time to have the saddle top dusted smooth with 220 grit sandpaper to slow string wear.