The Introductory Paragraph.

HP per second is absolutely applicable. In fact, that's the only thing that consistently improves about the skill as it's ranked up. You charge the skill, then use it don't you? That takes time, and during that time you get HP and use MP. Even if it's on a per-cast basis, you can still calculate it.

And if "mana->HP is what healing is", then why not include damage/stamina efficiencies with the combat skills like Smash or Magnum Shot? The answer is because it's not something people are interested in. Efficiency was added to the Healing table specifically to highlight the fact that it does not always increase with rank, which is a redundant observation since the hp and mp values are already in the table, and a subjective decision because some people may care only about how fast they can heal themselves and not care about the efficiency at all. The Healing page presumes that people care more about the details of efficiency than speed, or that efficiency is significant enough to include directly at all when readers can calculate it for themselves. In this way it uses redundant information to focus the reader's attention on particular facts because those facts are widely considered useful, just as the Windmill article could use redundant information to focus the reader's attention on particular facts because those facts are widely considered useful.

"HP per second" is heavily dependent on lag, so it is not a constant would not work at all. One can heal up to 4x per second when lagless and less than 0.5x per second when the player is halfway around the world. Also, like i said above the JP wiki has a much heavier weigh on the numbers that are put into the article. Even the client files are sometimes not accurate.