<p>I'd like to print a cylinder, 50 mm diameter, 200 mm long, with 1.5 mm diameter holes tightly fit like this:</p>
<p><a href="https://i.stack.imgur.com/i11dN.png" rel="nofollow noreferrer" title="3D rendering of a cylinder with holes"><img src="https://i.stack.imgur.com/i11dN.png" alt="3D rendering of a cylinder with holes" title="3D rendering of a cylinder with holes" /></a></p>
<p>The holes go all the way through from top to bottom.</p>
<p>I am using a Prusa i3 MK3S. With 0.1 mm detail and 20 % infill, printing one cylinder is going to take 5 days and 5 hours. I need at least five cylinders.</p>
<ul>
<li>Is the above setting appropriate for this job?</li>
<li>Is there any way I can reduce the printing time?</li>
</ul>

That's a hell of a print!
You are printing a model that has a highly complex structure there, with about 650ish holes, assuming there is space for about 2 perimeters between each hole.
Taking my standard 0.3 mm layer height and 0.4 mm nozzle using a 0.45 mm wide line, I sliced a 10mm high slice of the model for a first estimate of the expected print time - and came out with 2:21 hours. That means the expected print time with 0.3 mm layer height is in the area of 47 hours - or just about 2 days.
As a result, 5 days and 5 hours are in the order I'd expect from a 0.1 mm layer height print for the same nozzle, in fact, your settings seem to have a faster print speed than I do work with.
In general,  don't think this model is good for FDM Printing at all, due to many non-fully formed lines inside the model (yellow) and the red perimeters being a very dense pattern.
Solutions?
print faster
You might get a faster speed with a high flow solution, for example, using a long melt zone (volcano-style) or an even higher flow core-heating 3DSolex nozzle. The latter originally only comes in 0.6 mm and up, also mandating fewer holes, but in late 2021 CHT Nozles in 0.4 mm came to the market. This could drop print time some, but it'd still be a several days print job.
reduced pattern
Besides increasing layer height to drop printing time by the same factor, reducing the number of holes and as a result, spacing them further apart not only can increase the print speed but also make the print form more reliable.
Another alternative would be to alter the pattern from a circle to a hexagonal pattern: by using hexagons, the resulting pattern does not contain thin walls and might print much faster - depending on hole size, you might experience a drop by a factor of 2!
Printed differently
Going from FDM printing to a system such as SLS might be faster and more reliable while SLA/DLP would make this print not only fast and reliable but also trivial - if one can get a 200 mm high SLA/DLP printer, all three models should be able to be printed in one go at the same time!