The downfall timeline is the one that has the most confrontations with Ganon
Not necessarily true. The downfall timeline had Ganon strike 3 times: lttp, oos/a, loz.
If you place BoTW into the Adult timeline, then Ganon actually attacks 4 times: between OoT and WW, during WW, 10,100 years before BoTW and 100 years before BoTW. So the number of times Ganon attacked tells us nothing about the placement. Placing BoTW into any of the timelines automatically gives it the most Ganon attacks.