On some of the larger houses in my area (there is a lot of money here and a lot of big luxury homes) it is not uncommon to find 30+ window openings in the house - thats openings, not upper and lower panes. Especially the ones out by the lake or with views of the Hill Country

About a 12 years ago when I was selling and installing window blinds and shutters (trying in vain to get out of the residential construction biz) I sold a job with over 40 windows needing coverings. If only all the homes I sold to were like that I could have retired early!