As Dig said, not all wall chargers are created equal. Beefier, higher quality chargers are well worth the investment when it comes to charging large batteries in a reasonable amount of time. I have a pair of 26,800 mAh power bricks that I use as backup power sources for my electronics while I’m working - using a random wall wort charger out of the kitchen drawer, each brick takes as much as 24 hours or more to charge from near zero. Using a quality Anker USB-C 60w, 5v, 3amp, Power Delivery wall charger, each brick charges within a few hours. The difference is truly astounding.
Unfortunately, the Legend is limited to USB-A options, but a quality charger can still put a much quicker charge on the Legend’s 5500 mAh spare battery. I highly recommend virtually anything made by Anker. They can be a little bit more expensive, but extremely high quality products, and well worth the investment. As an example:
Anker Elite 24W wall charger, $10