While it may sound like a generalization, the actual answer is - it depends. There are basic rules that dictate starting points for placement, the actual "best placement" will vary with environments. Speakers placed in certain positions can alter sound. This is especially true of low frequencies, which can be placed in corners that increase low frequency sound. This does not mean it has a positive effect, but simply that it will redirect all radiated low frequency energy.
Having spent many decades in this industry, I can tell you that it is an interesting art of placing speakers. Most people set them up, and simply leave them. Some listen and reposition them, and listen again. While there are some definite placements you may not like, it really takes some listening to decide. Also, your decor may dictate placement, and your significant other may have a major vote too.
