Banner-making is a true art form, and to be able to find the balance for great quality of design mixed with a good optimized file size (for fast load times for the end user) is a true skill. Keep practicing, and keep creating these banners, and you'll be getting sales in no time!
In cases where the filesize is too large, I can cut the FPS by half which would result in a smaller file.
Otherwise are the most banners large so I am sure that the most customers know where they can use them and where not.
I will anyway help my customers as good as possible.
Thank you for your kind words.