Been using Squirt now for almost 3 years (well certainly over 2)…never had any problems with it…I do apply it generously though after the chain gets it’s 3 monthly degreasing clean. It gets coated, left for an hour (or allows me to go get a wash and food), I then give the cranks a few spins and leave it…in the morning, I give it another application.
Generally this leaves far too much on the chain but a few spins of the cranks and it seems to sort itself.
The chain stays good between rides and means it gets a quick squirt once a week (normally a Tuesday night after my weekly bike ride)…stays good for the rest of that week including any other riding.
Only thing I don’t tend to do is give each roller a single drop…I just coat the chain and then spin the cranks for about 20 seconds to make sure it’s properly coated.
Not had any problems in really wet weather (although a few mates who have tried it have had issues)…I suspect I’m applying too much of the stuff but it seems to stay on so no complaints from me. Easy enough to wash off (but to get it properly off needs a degreaser and scrub – but that gets done every 3 months).