The whole idea of the checkup is that on new bikes, things break in and need adjustment after the break in period, so it is a good idea to do it. Brake and shifter cables stretch, spokes get stressed, so these things at a minimum should be checked and adjusted.
I used to wrench at an LBS as an assembler, and we set up bikes right, in my humble opinion. We took almost everything apart, cranks off, checked that the fixed cup was tight, adjusted bb, headset, wheel bearings, all threaded fasteners lubricated. We greased and stretched the brakes cables and der cables, and stressed and trued the wheels. We did this on all bikes, even the least expensive.
If I built a bike and there was something major wrong with the bike when it came back for its 200 mile inspection, I heard about it.
If it were my bike, I would do all of the above or have someone you trust do it. A properly set up bike will last for many years with essentially no maintenance except for replacement of wear items (chain, freehub/wheel tires). I saw bikes come back that we had put together 3-5 years before, that were obviously used frequently, that still worked fine even though nothing had been done to them.
Il faut de l'audace, encore de l'audace, toujours de l'audace
1980 3Rensho-- 1975 Raleigh Sprite 3spd
1990s Raleigh M20 MTB--2007 Windsor Hour (track)
1988 Ducati 750 F1