The block regions feature was touted as a much needed improvement, and after many years, finally made it into Drupal 4.7. That said, I haven't seen that many people take advantage of it. This can mean (at least) three things:
I use the 4.7 region feature extensively. Before I converted my sites to 4.7, I used several methods to display adsense blocks. These ranged from the flexiblock module, to calling block_block('view', $delta) directly. When I converted my sites to 4.7, I junked all that in favor of regions. I even went further and had one "announcment" block at the top center of the page, also using regions. One problem I ran into, is that all blocks now inherit the styles of side bar blocks, and I had to work around that with some quick hacks. I agree with what Nedjo is saying, that normalization could help. I did not run into that issue myself, because most of my sites are one theme type of sites, however, I realize it can be a drag editing tons of themes.