plug checks can be used to fine tune, but you really need to know how to read the plugs. For basic, ballpark main jet settings, what I listed on plug colors are close enough.
Plug readings are really useful in 2 stroke applications, where being off by just a little bit seems to make a life or death difference to an engine.
on 4 strokes, like our bikes, I see a lot more tolerance to bad jetting before the engine is destroyed. That's why I recommended using the jetting database as a start. You might be happy with those settings and you could live with it and be perfectly happy.
again, be mindful that jetting can vary, so no one setting is "right", but needs to be fine tuned to gain the maximum. I prefer my jetting be a bit on the rich side than lean.
For me, rejetting has produced a little bit more top end HP, but the biggest gain was in the power gained overall to flatten out the power curve throughout the entire rev range of the bike. While before the bike was anemic on the lower end, had a nice midrange pull and died off towards the top end, the rejetted bike now pulls evenly from low rpm to redline.