I don't fill those in because you just know they are going to use data for marketing.

I do for larger/expensive purchases. For example, I registered all our home appliances. I use a separate email for all warranty registrations.

Never. I give companies as little info as possible.

Never. Data privacy aside, I can't be bothered to fill out yet another form or create yet another account just for one item I purchased. I also can't remember the last time I had something break on me before the warranty expired.

So my printer can rat me out? Fuck no

I do not, because if my product brakes, I would spent more money traying to make the warranty valid, that and loss time. It's such a useless procedure where you do a little work for the company for free (give them info directly), when people actually can earn money answering actual polls.

I want 0 spam in my life so I skip sharing info any chance I get. I don't register anything and I've never had that be an issue getting warranty work/replacement.