There is a Drop-down List in Defraggler to select Disabled, Run once, Run everytime.
But does it show the real status of Windows Boot Time Defrag BTD?
Other programs could have changed BTD before to another status.
Does Defraggler just tell Windows 10 to do this at the next startup? So it is a native Windows function?
If not, there could happen big trouble when more apps wanted to defrag at next booting.
So the actual status of BTD should always be shown to be sure, perhaps by radio buttons.
Defraggler makes an entry somewhere in the registry. But I haven't got the faintest clue where in the registry. When Windows boots the next time DF defragments (or tries to) a number system files BEFORE the bulk of the Windows (e.g. 7, 8 or 10) files is loaded and executed. DF uses a "defragment API" that is included in the Windows Operating System.
No, I don't think it will cause a conflict with other defragmenting tools.
There is a tool availble that shows what kind of programs are running (e.g. defrgamenting tools) before the bulk of Windows is loaded and executed. And that tool is a Sysinternal's tool called AUTORUNS.
AUTORUNS simply shows EVERY process/program that's automatically run with the start of Windows. I assume it will show DEFRAGGLER's pre-boot defrag process as well.