Hi Bob
I found it on another thread that you answered.

Is there a limit?

YES.
It seems that the max number of systems (lines) available are 12. You can only use 9 systems (lines) without the font size becoming automatically reduced.
There are 16 available spaces in each system (line) and with the addition of bar-lines, each space can be a complete measure (but with only one chord)
There are a number of songs I have added that I use 2 spaces per measure (8 bars per line x 9 lines = 72 bars) On lengthy arrangements, I add additional pages (each page is added like a new song)
Hope that's helpful,
)BOB

Thanks for the info
btw
I was looking for a tutorial and found one for the iPad but not for the Mac version.
With most tutorials I find myself wishing YouTube had a slow motion setting.
It took a few time watching to see the space(not space bar) button being pressed 4 times per measure.