Gonna start by saying: this could be user error!
I bought three black pads. I have four period panties I bought from another period product company. I bleed HEAVILY and CONSTANTLY. Before I knew about reusable period products, I'd use regular pads. I wore (and still wear depending on my flow) the heavy flow nighttime U by Kotex pads just as my normal pad. I should change my pad every 45 minutes. Sometimes on a really bad, heavy flow day, I'd change my pad every 30 minutes. I bleed through pads like nobody's business. I really enjoy my aisle pads, but on really heavy flow days, I bleed through them faster and more regularly than I do with U by Kotex pads. I also find that if my flow is really heavy while wearing the aisle pads, the front and back end slip around more, meaning I have to readjust the pad and line it up with my vagina pretty regularly. Again, this could be user error, but I do still find myself using single use pads near the beginning of my period and single use panty liners at the end, just because the aisle pads don't seem to want to stay where they need to and they don't absorb (and I probably don't change them) as much as the single use pads do. I am saving up money to buy another bundle of the maxi pads and other products as they are comfortable and aren't anymore noticeable while wearing them than single use pads. I have found I do prefer period panties to reusable pads, but that's also just a preference thing!