£10 PX 3mm Neoprene overshoes bought in October (I think), still going strong (Wish I’d got another couple of pairs now), perfect for my ~1h commutes (with the guards keeping spray to a minimum) in all but the worst deluge they’re OK, a wet weekend road ride it’s about 2-2.5 hours and saturation will overcome them and you start to get cold wet feet, not tried with sealskinz or polybag and two pairs of socks though, …
+1 for not over tightening shoes, good blood flow makes a big difference to your comfort…
Also if your shoes/overshoes do get wet on the way into work, take them apart (Don’t leave damp shoes in damp overshoes all day, they’ll just be damp for the ride home and freeze your feet) and stuff both with newspaper or tissues or whatever absorbent material you can lay your hands on… try to leave them near a radiator to dry if you can.
TBH the main route water will get into your shoes is by running down your calf, and that only really happens if you’re getting a proper soaking.
But yeah, Overshoes are the commuters friend…