Note that these options only affect how history data is retrieved from the archive. It cannot influence how data has been or will be added to the archive. Some PVs update at 10Hz and are archived once a minute. Others might update when changed via an operator screen, and are archived for every change. How a PV updates is determined by the front-end device that provides the PV. How it is archived depends on the archive sampling engine. The Data Browser only displays the live and archived data.
When "zooming in", the Data Browser will request samples for the new time range, which might reveal more detail and ultimately switch to "original" samples.
The optimized request type therefore tries to minimize the amount of data that needs to be transferred over the network and handled in the plot, while still providing enough information to see how the PV data behaved.
If you need the raw data for an extended time range for post-processing, you should use the Export View.