This article seems to apply to countries without inflation. In countries with inflation you don't grandfather any customers at all. You increase the prices to k

This article seems to apply to countries without inflation. In countries with inflation you don't grandfather any customers at all. You increase the prices to keep with inflation: sometimes you give them two-months notices (one month notice is required by law here), but if you don't plan carefully, the price may be outdated after two months and you need to increase again.