Using the new price experience for sales prices, allows for different price lists for customers, customer price/discount groups etc.
Maintaining them in the Price Worksheet needs improvement, since if new lines only can be added to the Standard price list, the whole idea of using several price lists falls.
When copying sales price lines from an excisting price list, you have the choice to copy excisting lines or Copy as new lines.
Copy excisting lines allows you to handle one item in several price lists, closing a price for example.
To add a new sales price line for the same item you use Copy as new line. The standard solution only allows new price lines to be added to a Standard price list, using the Price worksheet.
My suggestion is that the new lines should be added to the same price lists they were copied from.
There could be a boolean "New lines to Source price list" in the Price Worksheet, or in the Sales Receivables setup
that should allow for the choice if a Standard price list OR the Existing price list should be used for new price lines.