Bold \hlines for longtable

Question

I've searched the topic and found the following two answers.

Answer 1. LaTeX tables: How do I make bold horizontal lines (typically \hline)?

The best answer suggests to use booktabs. However booktabs documentation says:

A somewhat technical note: within a longtable, \hline and \hline\hline both produce a double rule (to allow for page breaks occurring at that point). But the booktabs rules do not. Longtable’s automatic doubling of \hline is questionable, even according to the documentation within that package. But doubled booktabs rules make almost no sense at all. In the unfortunate event that a booktabs rule should occur at a page break, then you will have to make the necessary adjustments by hand. (In general, this will mean deleting the offending rule.)

That's not the way it works. I don't want to make any more adjustments by hand since there are already a lot of things to be checked over.

Answer 2. Longtable does not break correctly when used with \specialrule instead of \hline

Here the author have faced the problem described above. He'd tried to use \specialrule from the booktabs package but the output at page break was buggy. The solution was to use normal \hline with previously adjusted \arrayrulewidth. Unfortunately, this can be applied only to the whole longtable, but not to the individual \hline.

Answer 1

You seem to be lacking a question, as you just quote two answers, but an answer to a possibly related question is

 \\
 \noalign{\global\arrayrulewidth0.5cm}
 \hline
 \noalign{\global\arrayrulewidth0.4pt}

Answer 2

Easiest way (taken from here):

\newcommand{\myhline}{\noalign{\global\arrayrulewidth1cm}\hline
                      \noalign{\global\arrayrulewidth1pt}}

or

\setlength{\doublerulesep}{0pt}
\newcommand{\myhline}{\hline\hline\hline}