Set point size independent of line weight - gnuplot

Question

I have the following line styles defined in gnuplot:
set linetype 1 lc rgb "red" lw 3 pt 7
set linetype 3 lc rgb "red" lw 1 pt 7
It appears as though the points derive part of their size from the lineweight. I'm using these styles inside of a plot for loop with linetype cycle using the same style for a cspline and the corresponding points, so I don't see any easy way to just define a separate style for the points.
I get results like this:
The points respond to pointsize but the point in linetype 1 is still slightly larger (presumably from the thicker border).
Is it possible to get the points in these two styles to be the same size?
In response to Miguel's comment, a more complete example of my use case is:
filenames = "A B C D"
set linetype 1 lc rgb "blue" lw 3 pt 7
set linetype 2 lc rgb "red" lw 3 pt 7
set linetype 3 lc rgb "blue" lw 1 pt 7
set linetype 4 lc rgb "red" lw 1 pt 7
set linetype cycle 4
plot for [file in filenames] file.".csv" \
using 1:2
title file \
smooth csplines, \
for [file in filenames] file.".csv" \
u 1:2 with points notitle
linetypes 5-8 get set by the cycling and are used by the last part of the plotting command. Recommendations on another way to do this would be welcome!

Answer 1

For your very specific case you can set more styles, and do it rather automatically with a do for loop (reusing your code):
filenames = "A B C D"
do for [i=0:1] {
set linetype (4*i+1) lc rgb "blue" lw (i == 1 ? 0 : 3) pt 7
set linetype (4*i+2) lc rgb "red" lw (i == 1 ? 0 : 3) pt 7
set linetype (4*i+3) lc rgb "blue" lw (i == 1 ? 0 : 1) pt 7
set linetype (4*i+4) lc rgb "red" lw (i == 1 ? 0 : 1) pt 7
}
set linetype cycle 8
plot for [file in filenames] file.".csv" \
using 1:2 \
title file \
smooth csplines, \
for [file in filenames] file.".csv" \
u 1:2 with points notitle
With some simple data files:

Answer 2

For some terminals the size of filled point types depends on the linewidth because they have a border. This is the case for all cairo-based terminals (pdfcairo, pngcairo, wxt and cairolatex), whereas other terminal like svg, postscript, qt don't show this behaviour.
As test case consider
set linetype 1 lc rgb "red" lw 3 pt 7
set linetype 3 lc rgb "red" lw 1 pt 7
set samples 11
set style function linespoints
plot x lt 1, x + 0.5 lt 3
Considering that you want to have the linepoints samples in the legend, you're best choice is to reduce the point size a bit for the line type with the larger linewidth, like
set linetype 1 lc rgb "red" lw 3 pt 7 ps 0.9
The choice of the scaling factor must be determined manually.