The DJE-056 Mao scene is only 20 minutes long, so she swallows 40 loads in only that time (2 loads per minute).
For comparison, MDLD-359 has 40 loads in 27 minutes = 1.5 loads per minute (and features fucking). The MIGD-380 scene 8 has 36 minutes of swallowing 45 loads (1.25 loads per minute). The MKMP-059 scene is 45 minutes long but also has extensive fucking at the end, which slows down the swallow rate (0.9 loads per minute). DJE-025 is also 0.9 loads per minute.
So, in summary, I don't think there's any scene that features such a large amount of swallows so quickly as Mao Hamasaki's in DJE-056.
Honorable mention to SDMT-417 scene 4, where Ryoko Hirosaki swallows 16 loads delivered to her mouth in only 5 minutes, a rate of more than 3 per minute. It doesn't have the volumes of the other scenes but the loads are delivered quickfire.