When an investor has a discretionary account they permit the broker to decide on which securities to buy and which to sell.  This also allows the brokerage firm to decide on what price should be pair and what should be received.

When you hold a discretionary account you need to monitor to make sure that the broker has not engaged in any kind of excessive trade with your account to earn just a bit of commission.

Brokers are likely to churn accounts beyond what you prefer for minor profits.  So unless you trust your broker in full you need to keep a watch in what is happening with your account.

Either way it is better you have a track of what is happening with the account to prevent long term shocks.