Am I right to assume that if new scapes are emerging, before the old scapes finish blooming out, that I'm seeing instant rebloom? Both "Helicopter" and "Adena Inferno" are exhibiting this. The new number of scapes for each plant corresponds with the number of blooming scapes. hard to get a picture including all, this is the best I can do.

The normal growth module for perennial plants is to produce a number of leaves and then flower. When a perennial reblooms it typically produces a second set of leaves and flowers again in the same growing season/year. So instant rebloom would seem to mean that the daylily produces a scape and then does not produce any leaves but flowers again. Therefore instant rebloom would mean two normal scapes side by side with no leaves in between them.

Thank you, Maurice. I have so much to learn. These are not in close proximity to the existing scapes, so are from new fans/plant increase?

Daylilies flower by producing a fan of leaves and then a scape from (usually) the centre of that fan. The reason that it is usually from the centre of the fan is because the fan has reached maturity when it produces its scape and it is basically complete. The fan finishes its cycle of growth at around the same time it develops its scape by producing a replacement fan - a baby fan. The baby fan is usually either one side or the other of the scape and right next to it. The new baby fan can grow very rapidly because the crown is mature and can help it by providing it with some of its stored nutrients so that it gets a good and quick start to its growth. Depending on how quickly the new baby fan grows it may reach its mature size in the same growing season or the next season (or even later seasons). If it reaches its mature size in the same growing season it may produce its own scape and flower. That is rebloom. I would not consider that rebloom from fan increase as the previous fan is replaced by the new fan so there still would only be one fan. How quickly the new fan grows (how many leaves it makes before it makes a scape) may depend on its growing conditions (we do not have any information that I know of about that).

Sometimes the mature fan produces two new baby fans. One of those fans would be increase since instead of one fan there now would be two fans. I do not know if there is any information about whether one or both of those fans can flower in the same growing season and produce rebloom.

In my garden, I seldom examine the crowns to determine whether the new scapes are originating from the original crowns. If I have a "flush of blooms", and that is followed by a new set of scapes that bloom while those first ones are blooming I consider that to be instant rebloom. If there is a period of time between the first flush of blooms (a week or two maybe longer) in my garden that is called rebloom. Now I know Maurice is much more scientific and technical than I, but I wonder if when a plant is registered with instant rebloom and rebloom if the scientific terms are the ones used?
My way is just more useful to me in my garden. How do others determine instant rebloom and rebloom in your garden?

I went to the AHS site to get the definition of instant rebloom and rebloom, but that dictionary appears to be still under construction.
I looked at introduced and got "Interveinal chlorosis" . I am lost with the new site so far.

Use the old daylily dictionary until the new one is sorted out. I don't think you'll find instant rebloom though, it's not an "official" term.

https://www.daylilies.org/ahs_...

@Seedfork
Instant rebloom based on whether the two flowering scapes have overlapping flowering times or not is likely to be due to growing conditions, that is environmental. So a cultivar might show rebloom in some growing seasons and instant rebloom in other growing seasons depending on temperatures, rainfall/watering, diseases, weeding, division, fertilizing, etc. over two growing seasons.
Instant rebloom that is caused by two scapes being produced in succession without an intervening vegetative flush of growth (leaves) is likely to be genetic and a more stable characteristic of the cultivar/plant.

I seem to notice the new scapes, but seldom do I ever really notice a new flush of leaf growth. I have been in the garden this morning pulling old leaves (thankfully not rusty leaves) and I was not very observant of any new leaf growth, but did see new scapes and buds. I will try to pay closer attention to the leaf growth.
I do recall when cutting all the leaves back a flush of new growth appearing, but I am not sure that counts. It seems I am constantly pulling dead and dying or diseased leaves. I guess I just expect the plants to produce new ones, and do not pay much attention to the process.
This seems to be the time of year for me that the plants in my garden are starting to put out new scapes and buds, and the time when the first set of leaves have matured and are starting to get old and tattered looking. So I will be busy pulling baskets of them off. Just pulling off all the tattered old leaves can make the garden seem as if it has miraculously gone through a transformation and grown new leaves. I will be scouring the plants for new leaf growth over the next few weeks.