Of course using the hood is "best practise." But on a trip to NYC, I wanted to keep my MZ-S / FA 43mm combo as "pocketable" as possible. I used a pinch-on 43mm cap, with no hood. The SMC coatings are really good -- I trusted them and was not disappointed.
Here is an album of those shots, almost entirely made with that combo, no hood used. In only one example, shooting directly into the sun at Times Square, is there flare. But the angle of the sun probably would have yielded flare with the hood too.
https://www.flickr.com/gp/davidwscott/351hY0
By the way, the panorama shots were also made with the FA 43, stitching multiple frames of film together.
In other testing, I found even very expensive UV filters were robbing me of contrast and detail. As soon as I saw the proof, I quit using them.