Ash buildup in RMHs

Hi all;
Went out to restart the greenhouse RMH today and realized it was time again to clean out the ash buildup.
Some of you may be thinking, but I thought RMHs hardly had any ash at all.
This is true, beyond the riser there is very little ash.
However, before the riser, there is plenty of ash.
Today I took out approximately three inches of crusty ash.
When your firebox is only 13" tall, three inches is noticeable.
This is apx. a month's buildup with my extremely long burning batchbox.
A normal batchbox in an insulated home might only need scooping once or twice a season.

My 8" J-tube only needs ash cleaning once every couple-few weeks. As the fire goes to coals and before adding a new load, I push the glowing coals back into the burn tunnel under the P-channel blast, where they get reduced to almost nothing. The ash at the feed tube floor gets compressed to a hard crust an inch or so thick, and depending on the wood being burned, the ash farther back can be a soft heap or crusty. I can burn a square cris-crossed stack of wood at least 4' tall before I need to clean the ash. I could go longer but usually don't. I have only properly collected my annual ash production once or twice, and had less than a 5 gallon pail of ash for the winter. This is in upstate New York, zone 5. Oh, there is NEVER any coal or combustible material left in my ash pail.