From Mark Evanier:
Also notable about Aparo were his meticulous work habits. Except for a few brief exceptions, he always pencilled, lettered and inked his own work at the rate of one page per day -- no more, no less. He'd pencil that page in the morning, break for lunch, letter it and then almost always have it finished by bedtime. This was possible because editors found him so trustworthy that there was no need to have him show the work in the pencil stage. They could just send him a complete 22 page script and then, 22 workdays later (plus travel time), they had the finished art. In the DC offices, there would sometimes be panic -- "We need to have a script ready for Aparo by Tuesday" -- because he delivered like clockwork.
You have to admire that discipline and dedication. A lot of creators today would do well to follow his example. He will be missed.
The panel image above is from Will Pfeifer.