In our experience, this is by far the norm, and exceptions are rare, at least starting with IJM supplied curves. I for one would not expect to use the droplet repeatedly on the same curve and get good results, I only use one iteration and very, very rarely two.
If the release is imminent, as you said in another thread, then there's little point speculating about what's going to be in it. But I'm a little confused. I think I've read most of the comment about it, and initially it just seemed to be an error correction tool to use in conjunction with the droplet, but in the latest newsletter IJM says:
And now - we have a workshop release version of the Piezography Profiler app. This may be the best reason to attend a Piezography workshop. You will learn how to perfectly linearize your Piezography system as well as create your own custom curves for non-supported papers. Master you own domain!
The underlined part of the quote implies that it's more, and will allow us to create our own custom curves, a capacity I'd certainly be prepared to purchase. We will see soon enough.
I realise that you've put a lot of work into this new package, and clearly you want to talk it up compared to the droplet. But simply to say that the 21x4 + droplet does "not a very good job" as a general statement flies in the face of many users' experiences, and particularly these ones. By all means promote the virtues of what you're producing, but simply denigrating the ingenious tools that Mr Harrington has produced lowers the tone of the forum. Especially as his droplet seems have pushed IJM into allowing users to self-support to a much greater extent, something that can only promote the uptake of Piezography.