I became addicted to my smartphone within about a week. Having perpetual, low-resistance access to email, Signal, news, browser and podcasts and having my smartphone in constant physical proximity resulted in a notable acceleration in frequency of checking these apps. After a day or two, I began to find it difficult to leave my phone alone. I would put the phone in sleep mode, yet find myself picking it again, sometimes before even a minute was up. I invented a stream of reasons to check my phone and I found these impossible to resist, establishing a pattern of consistent little failures in discipline throughout the day.
I have a similar dedicated device setup but over the past few months have had to shift most of my computing onto my smartphone. After the shift, I've had a similar experience where I find myself reaching for my phone more often than I'd like. It's way too convenient to just "look that thing up" or "add that thing I need for the house to the cart". Personally, I don't mind carrying around or using multiple dedicated devices. I find the friction helps slow the impulses and makes me more intentional. Ultimately, my plan is to eventually transition back to dedicated devices. I've already done it to an extent with my Innioasis Y1