Not here to argue but I’m not sure you are understanding the point. 

Yep. An automatic watch can have 300m water resistance but if dropped on concrete from five feet it will more than likely suffer damage to the movement necessitating a watchmaker’s care. Been there. The fact of the matter is that mechanical time pieces are relatively frail things and significant WR doesn’t make them more rugged. Good build does, and that varies from manufacturer to manufacturer. 

“…the WR implies ruggedness of a watch…”

Is this truth or perception?

You are not alone. While there are legit stories out there about flooded watches, in the end the ugly truth is that user error usually led to the mishap. Even the Omega PO Ultra Deep won’t survive some poindexter leaving the crown out, and the Speedmaster, which passed NASA‘s scrutiny with some of the most torturous tests ever put to a watch, won’t survive someone who doesn’t know you can’t press the pushers underwater. The bottom line is that we have been conditioned to believe that 50m is simply not enough for everyday use, but there is no evidence to support that. 

If you can stretch your budget a bit you should take a look at the Hamilton Khaki King automatic. You can find it at Jomashop for £338. 
The quartz version sells for far less but is harder to find. Hamilton is one of the best Swiss entry level watches around. The water resistance is 50m / 165ft which is more than anyone will realistically ever need. 

I generally sell watches I don’t wear. It does not make much sense to me to keep them sitting around. Having said that, starting this year in the U.S.A. selling personal items or accepting payment for the sale on certain online platforms is going to be a pain in the arse! If sales for the year total $600 or more the online platforms will issue a 1099-k and you will have to show a loss / break even on the item in your tax return or pay capital gains taxes on any profits from the sale(s).

It is enough to put you off selling random watches here and there. If the U.S. government is so hard up they need to reach down and tax the $20 profit I made on the sale of my Alpinist… 🙄 

My wrist is about the same size so here are some thoughts derived from years of experience and many mistakes made.

You will hear people say wear what you like, but the truth is there are watches that fit and watches that don’t. With an 18.1cm wrist I would stick to watches with a 36mm to 41mm case, and a lug to lug measurement of no more than 48mm. If it is a dive watch you can stretch to 42mm but I wouldn’t flirt with a lug to lug that approaches 50mm. The height / thickness of the watch can affect the wearability but it isn’t as important as case and lug size. Having said that, in the sizes I am suggesting I would stick to watches with a thickness between 11mm and 14mm depending on the case size. 

The bottom line is that the day of the big watch has come and gone. Your sweet spot is:

Dress watch 36mm - Daily driver 39mm - Sports / Diver 40mm to 42mm 
 

Stick close to that and you will be happy.