My son is a 2021 OF P5 commit. He sent two rounds of letters. One at the beginning of the summer between his sophomore and junior year and another mid-way through the summer season. Some were to schools that were already following him and those Emails were more about sharing his schedule and his travel coach's contact info. The rest were introductions (also with schedule and contact info.). We did not have video in the first letter but we had video in the second. I do not think the letters had a huge impact, except perhaps a memory tickle/putting his name on a list of someone to follow. I would say conversations from his coaches and his performance at events (Jr. National Showcase and WWBA 16U in particular...Future Games was a great event as well but he was pretty far down the decision path at that point) is really what set his recruiting on fire. However, I also agree with a previous poster that preparing and sending letters it is a good muscle for kids to exercise no matter what. It forced him to really think about where he wanted to go to school and why. I do believe that we are in different times now and that direct contact is actually helpful to coaches. I listened to a podcast from my son's future head coach and he said because of COVID, his staff is sitting around and watching a ton of video. Josh Rudd's videos also talk about the art of the letter. FWIW my son went to four camps total over two years (including where he is going) and all four followed him closely after camp.