The purpose of the $convert report command is to get an idea about how beneficial SBD to STEEM conversion is. It does this by querying for the last 100 fill_convert_request virtual operations, then calculating an average.
It's just a mini-report about the latest conversions. This command does not perform a conversion.
So why would you do this? Because you're trying to decide if using the convert feature is more beneficial than selling SBD on a market (internal or external). How does this help you determine which action is best?
The answer is: I don't know. It's just data for you to look at and make your own decision, keeping in mind that the price filled from the last 100 requests is not an indication of what the price will be in 3.5 days. This is because if you initiate a conversion request now, it will not fill for 3.5 days. Got that? In order to know if a conversion is beneficial, you'd need to know the future.
$convert [limit] [chain]
By default, the limit is 100, chain is steem.
$convert
You can see that, in the above example, 100 requests only spans a timeframe of 12 hours. This is not always the case.
$convert 3000 hive
In fact, you can see that 3000 requests spans 15 days, in this example. This means the data crosses over from Steem to the Hive genesis, at the time of writing.
See: How do Steem Dollar to STEEM conversions work?
Remember:
... it is possible to end up with more or less than $1 USD worth of STEEM per SBD at the end of the conversion. This is an advanced user feature, and is currently only available to users using external wallets.