The situation: In the U.S.A. it is common for companies to offer a 401K or 403B retirement plan.  These are typically a pre-tax payroll deduction that is directed to an investment firm to buy stocks or mutual funds for the employee in a fixed amount.  

This is commonly done by directing the payroll deduction into an cash account with the investment firm (e.g. Fidelity Investments) belonging to the employee.  
Then, on a regular schedule, investments are purchased from the cash account.  

For example, from every bi-weekly paycheck one might have $225 directed into the cash account and then $75 of Stock A, $75 of Mutual Fund A and $75 of Mutual Fund B would be purchased using the cash account.  The dollar amount is fixed for the purchases, the quantity varies based on that day's price of the investment. 

The ability to schedule investment purchases (i.e., Buy Shares) would save much time spent looking up the price on a given day and/or the quantity purchased.  

Of course with three variables (Total Amount, Price and quantity) this would mean the scheduled transaction would need the ability to use that day's price for the security.    Hmmmm, a bit of a challenge I would say.  Maybe something to ponder on.