"(4 on this machine)" sits in whatever the two spinners leave of a fixed 400px
pane. That fit on one machine and ellipsed to "(4 on this machi..." on another,
which left the hint existing only in the tooltip on exactly the machines it was
written for.
Now "(4 at a time)": six characters shorter, and short enough to fit that column
with room over rather than by a hair. Why the number is smaller than the setting
is what the tooltip is for; the number itself is what has to be legible. Classic
reads the same string into its tooltip, so both UIs move together.
Layout geometry is untouched on purpose - the spinner widths and the row structure
are the part that was reported as clean.