Why is iceberg, cover and bracket order not allowed in AMO, never really understood the logic. Ideally all the order types should be available in AMO as well as i place most of my orders the previous night post my analysis hour.
Cover and Bracket orders are algo orders that are directly sent to the exchange, and these are subject to limits for that day and that time. These usually would have high rejection rates if accepted when markets are closed and sent when markets open. My guess is the rejection rates would be over 60-70%, will be frustrating for users and of-course more time consuming to check reason for failures and place fresh orders then.
In addition to that, these orders, including Iceberg orders take time to be sequenced one behind each other and validate with risk management systems before sending to exchanges. Iceberg orders, we have users placing upto 99 trades, while these validations takes fraction of milli-seconds, for large legs with 99 legs, the time taken goes up as every trade has to be validated, submitted, executed and updated to positions and order-book. When markets open, prices are very volatile, any additional times taken - will result in slippages that you will visibly end up seeing in execution.
Idea of Iceberg orders is to give you time-priority on execution. Now we have many large trades actively using this, we recently even mentioned that over 8% orders on Dhan are above freeze limits.
We made significant changes on Iceberg orders based on usage and feedback, here is a post on how they have evolved. Updated: Iceberg Orders now get even Better Experience on Dhan