How are you entering the notes?

There are ways to have Finale guess clefs, None would do what you want in this example which is to read your mind. Having three notes preceding the bass clef that are Bb and lower — how will you tell any preference setting to know that?

It's much easier than reading the user's mind, what I ask doesn't require it at all.

For instance, it could be achieved by telling Finale that, if the following conditions are met,

1. there are notes falling in the n-th (let's say n=2, 2nd) ledger liner or even outer
2. there are m (let's say m=3), or more, consecutive notes that meet the first condition

then, it must change the clef to another one at which those notes detected to meet both conditions fall inside the staff.

(of course, the first picture I uploaded would not be changed exactly to the second one using this method, unless there is also the option of saying where clef changes can be done: before a beat, inside beats...)

I suppose this option doesn't exist, but I'm a little puzzled about it. It would be a very helpful and simple tool.

I entered the notes pasting, transposing, using retrograding, etc.

This sounds like a job best assigned to a plug-in that an be assigned to a range of measures and then called with appriate parameters set by the user.

Ok, I see... And is there a plugin that could help me with this?

What Adrian says. What you appear to want is more complex than Finale Preference dialog boxes currently allow.

It should be able to be scripted. You would highlight a passage and run such a script according to the rules that you have defined. You don’t state what version of Finale nor your OS. Basically, plug-ins are complicated scripts but there is a plug-in called FinaleScript™ to help with that. Here’s an overview from the 2012 Windows manual.

https://usermanuals.finalemusic.com/Finale2012Win/Content/Finale/FinaleScript_plug_in.htm 

Thanks, I have taken a look at the link. However, I haven't found a way to specify conditions in scripts, so maybe it would not be feasible...

Another option could be, instead of changing the clef, to add 8va, 8vb, 15ma or 15mb lines automatically.

…

For instance, it could be achieved by telling Finale that, if the following conditions are met,

1. there are notes falling in the n-th (let's say n=2, 2nd) ledger liner or even outer
2. there are m (let's say m=3), or more, consecutive notes that meet the first condition

then, it must change the clef to another one at which those notes detected to meet both conditions fall inside the staff.

…

Quaerendo Invenietis,

Not that it matters much, but …

If those conditions are used on the graphic you attached in your first post, then the clef change to Bass Clef should happen already at the barline.

Or am I missing something?

>However, I haven't found a way to specify conditions in scripts, so maybe it would not be feasible...<

Scripts are how you tell any app to perform under specific conditions. You have already specified these conditions. Now you need to do it in a way that the OS and Finale understand.

All scripting environments fall into one of two types:

a) In one, you tell Finale what to do—you've already given an example of what you want. If you can put it the way that Finale needs to see in a script, you're good.

b) In the other, you show Finale what to do by performing the task while the script recorder is running. When done, you can edit the script to handle or ignore any variables as you see fit similar to (a).

Once you learn to think the way that Finale and the OS need, scripting is easy. That does not mean it's always fast nor does it mean there isn't a learning curve. Scripts are unforgiving in that a mistyped character will keep one from running properly but, once you figure it out, you'll be amazed by what you can accomplish. When I worked for the phone company, I wrote a few that took me some hours to get right but they saved me hundreds of work-hours every year by allowing me to concentrate on the core part of my job. I let the scripts do the mindless (literally) busy work.

It all comes down to this: What is your time worth?

Why not just move the low notes to the bass clef staff?

...

Quaerendo Invenietis,

Not that it matters much, but …

If those conditions are used on the graphic you attached in your first post, then the clef change to Bass Clef should happen already at the barline.

Or am I missing something?

...

Peter Thomsen, you and Mike Halloran are right, that example doesn't follow the rules I suggested. A better one could be this:

transformed into

Mike Halloran, you are also right when you say that creating a script of this type may not be worthwhile in order of saving time. But is not just because of time-saving, but because I find a little annoying to have to be continuously thinking about the best clef, about when to change, making the change itself, etc. I have not found the way to record the script (my Finale version is 2014.0.3163), but I will try again.

Sometimes it's better just to do things manually, until Finale manages to implement Mike Rosen's "Mind Reading" plug-in (suggested many years ago) which simply reads your mind and writes the music for you.