Kinda seems like your heading in that direction of a does it doesn't it work thread by your follow up questions.

To answer you original question.. Yes a base layer in theory should be enough. Do I use layers? Yes. I sometimes have to unzip the outer layer if the temps get a little warmer than expected. In that case I'm glad I had base layer on as well. On the opposite side if it gets cooler than expected I have enough layers to stay comfy. I have noticed this year.. actually last weds night when I had 3 deer not 15 feet from me at ground level not see or wind me that I became a much bigger fan of scent blocker. The deer i never knew were there and vice versa until I moved to set down my bow while taping 20 other deer in a soybean field. We could argue this point until the end of time and there will be those who think it works and those who don't. Just like scent and lures, but thats another issue.