Roy Lewallen wrote in
:

....
A choke at a high-impedance point doesn't do much, since there's no
substantial current at that location to block. You should put the
choke about a quarter wavelength from there where the current is
nominally high. The presence of the choke can move the locations of
high and low voltage and current points, so you'll need a choke at
least about every quarter wavelength to make sure there's no point
where substantial current can occur.

Roy, NEC models suggest that lossy chokes (eg suppression sleeves or cores
where Q is very small) don't modify the current distribution much unless
they are of sufficiently large impedance, and that introduction of low Z
chokes just introduces another loss without much impact on the current
distribution or resultant antenna pattern.

The magnitude of Z needed to be effective in forcing a current minimum at a
point might be quite impractical to implement using suppression sleeves, so
the time honoured insulator looks the better solution.

Owen