Recently I have been looking into ways to improve the initial set up stages using ADA soil.

A few things have come out of that.
Purigen is very good as is activared carbon and Zeolite.
Purigen is better than carbon is many ways , however, carbon later becomes a better bio media as does Zeolite.

So it's not removed.

The other thing, and Amano does this also, although very few ADA converts ever talk much about the real applied aspects of ADA mainteance: for the first 1-2 months, do 2-3 X a week 50-70% water changes.

Yes, Amano does them almost every other day for the first month, that's how he deals with the NH4(and NO2). This does not harm a tank because it's new and algae spores are not settled in yet which takes a few weeks.

If you do both water changes and chemical removers that later just turn to biomedia, this works well, is fairly cheap and adds redunacy/back up.

CO2 etc is brought in as well after each water change, waste etc is removed as a source of NH4, + NH4 present from the ADA AS as well.

After about 1-2 months, all the bacteria has settled in, the ADA AS is now namely NO3 from bacteria(except inside the grains, the outer surface has been oxidized/colonized with bacteria).

Plants can keep up with the leaching of NH4 at this point.
When Feedbacks are exceeded for too long of a time frame, then you have issues.

Regards,
Tom Barr