It's hard to give an exact number. Marvel has rebooted their comics several times over the years, but the count can vary depending on how you define a reboot.
Marvel's reboots of comics are numerous. They do it to introduce fresh takes on characters and storylines. Sometimes it's a soft reboot, and other times it's a more radical change. So, there's no precise count.
Well, it's tough to say exactly how many times. The reboots happen when they want to refresh storylines or introduce new takes on characters. It's happened multiple times across different franchises and story arcs.
The comic Flash typically has more established feats of speed compared to the DCEU version. However, different versions and story arcs can sometimes make the comparison less straightforward.
The significance can vary. It might be to update the story for a modern audience, to fix plot holes in the original origin story, or to introduce new elements that fit better with current trends in storytelling.