The secret to understanding lens hoods is that the purpose they serve is to eliminate incident light
that isn't apparent in the view finder. If you choose to include a a light source in the frame you can judge the flare effect yourself.
Incident light that strikes the objective lens from an angle outside the direct VF screen image has the potential to seriously degrade contrast, especially noticeable in the out of focus areas. Night club/theater/entertainment venues with lots of incident light sources are a common example of this effect -- and the very place most people shun a hood to avoid attention. (That's when you make lemonade and call the resulting flare and muddy contrast an "artistic moody ambiance", eh?.)
Modern coatings help a lot but using a too short lens hood's about like holding a napkin over your head in the rain instead of an umbrella. Short hoods that are designed for full frame zoom lenses at their widest FL are fig leafs at best.
Inconvenience is the price of crisp, contrasty images -- you make your own compromises there. Integral, sliding lens hoods attempt to help solve the problem with variable extension.
Some options discussed here:
https://www.pentaxforums.com/forums/do-yourself/135542-diy-lens-hoods-no-math-required.html
H2