Claims about how many characters you can learn in a day, a week or a year vary widely. In The Chinese Language: Its History and Current Usage (2006), professor Daniel Kane wrote (page 55, my emphasis),
The maximum rate for the absorption of characters, especially at the beginning, is about 30 a week.
Professor Kane makes no reference to Heisig's method; as far as I can remember, his estimate is based on what his students managed to learn.
On the Web, you can find many other estimates, some singificantly lower, some signficantly higher. An element of bragging cannot be exluded.
On Quora, Vanessa Pacheco claimed,
I used Heisig's method with Japanese Kanji and memorized the 2100 in 2 1/2 months. It took me a few months after that to bring my reading up to speed as well.
If we assume that 2.5 months is 75 days, 2100 in 75 days corresponds to 28 characters per day.
The blog post The Chinese ABCs are not as easy as one, two, three on Impossible Chinese from January 2016 contains the following quote:
It’s been around 25 days since I started learned Chinese again, and I have fallen short of my original plan to learn 50 characters each day from Heisig’s list of the 3000 most common characters. If I had adhered to that schedule, I would currently “know” 1250 characters. Instead, I only know around 1115. While I have continued learning 50 new characters per day, not all of those characters are a part of Heisig’s 3000 most common ones. (...) As a result, I am not going to get through all 1500 characters in 30 days. It will take more like 35. Or 38. Or 40.
1500 characters in 40 days (assuming the author's "pessimistic" estimate) gives an average of 37.5 characters per day. Even though this is lower than Heisig's 54 characters per day, it is still at least seven times higher than professor Kane's average.
In a follow-up post written in February 2016, the author of the above quote wrote,
My original goal for the first three months was to learn the 3000 most common Chinese characters. I learned 1500 in just over 30 days and there are now 50 days and 1500 characters remaining. That means I need to learn at least 30 new characters per day to reach my initial goal.
However, he also adds, "I nearly burned out learning the first 1500 [characters]" and therefore plans to continue learning using Anki at a less intensive rate, possibly reviewing a maximum 30 characters per day. (This does not imply that he plans to learn 30 new characters per day but that 30 new characters will be added to his review queue; these characters are repeated later at increasing intervals until you know them.)
The blog post from Impossible Chinese is the most extreme claim I could find for using Heisig's method. There is a blog post on Sensible Chinese that claims there is a method to learn 100 characters per day, but in view other testimonies from learners of Chinese (not just the ones I quoted), I am skeptical about this claim.