I setup a daily $15 purchase of BTC on coinbase, something is amiss. Maybe y’all can help me understand.

I swear they somehow are only buying at the highest price. Am I crazy? Every purchase has been at different times each day. Some as soon as 9 hours apart, 7pm and 4am, and others as much as 20 hours apart. But, in 5 days, no purchases have happened when BTC is at its lowest cost, almost every time at its highest. Are they maybe trying to mimic by BTC amount purchases when I setup the recurring buy? I am at a loss. I’d prefer to keep the convenience of the auto buy, but also I’m wondering if I should just start buying the same amount when I feel like it each day. Does anyone have any insight or similar experience?