@Genie484
I'm no way an expert, and a lot of this information is new to me about my own body, but I think.....
Rapid surge - this means you have less notice that you are about to ovulate, so you will hit peak fertility very soon and be at optimum time to DTD
Gradual - it's a longer build up to your peak day/s ovulation.
I found this quote on the internet;
LH surges that result in ovulation can varying configuration, amplitude, and duration.
The onset of the LH surge can be one of two types:
Rapid onset, when it occurs within 1 day (42.9%)
Gradual onset, when it occurs within 2 to 6 days (57.1%)
Regardless which you have, the egg released can only be fertilzed for 24 hours. Sperm live for about 5 days, so I guess the advantage to gradual is you can ermmmm....let the sperm build up inside you waiting for the egg.... Sorry 😂
Rapid, this is maybe why drs recommend DTD every other day so if your rapid you'll have some swimmers lingering in there at short notice.
I hope that made some kind of sense, if I'm right, ladies feel free to correct me!