Most IR trained people want to maximize their suite time, either doing elective or urgent cases. You could join a large group with only 1 or 2 suites and I guess you'd have a lot of downtime, but why would you seek out that experience? And let's not forget that a lot of your procedures will be elective, and many will be on patients that are followed longer term with multiple aneurysms, a big AVM, menigiomas for devascularization, etc. That means significant clinic time devoted to your IR practice even when you aren't running a room. So your week can be pretty full just with IR-related stuff once you have a good referral base and an equitable chunk of suite time.
You should always do what you enjoy, and if you want to integrate more stroke into your practice when you aren't in the suite, then you could do that. The opportunity cost of that time is enormous, but it's up to you. Some places are looking for board certified vascular neurologists, but I'd be surprised if they're looking to satisfy an IR hire and a vascular neurology hire in one person. If you're hired as the only certified vascular neurologist at a CSC, then you're basically running a division and supporting the continuing CSC accreditation, in addition to your IR practice. That sounds nuts.
If you don't want to do ICU, then you shouldn't because you'll be miserable through a grueling fellowship. RVU generation in the ICU is a hell of a lot better than stroke, but still not close to what you can do procedurally as a neuroIR attending. Many neuroICU people do acute stroke and inpatient stroke care on the side, myself included, regardless of the lack of formal accreditation, even in famous medical centers. But for people looking specifically to hire a certified vascular neurologist who has a lot of outpatient training on secondary prevention and sonology, the ICU training won't sway them.
Both vascular neurologists and neurointensivists are in high demand in non-academic settings, sometimes for the same jobs, but often for different roles. In academia it's a bit different, as the major centers get more quickly saturated with neurointensivists because there are only so many unit weeks to go around. But if you're IR trained, your priority is going to be finding a good fit for your IR practice first, and then figure out the rest.
Bottom line, you're right. Nobody does "100%" suite time, just like neurosurgeons don't do 4 cases a day 6 days a week. There are other mandatory IR-related activities, including clinic, conferences, administrative duties, teaching, etc. If you do all of that and you still have more time left over, then stroke or ICU service time is a real option, particularly if you don't have enough IR patients to proceduralize, or rooms to run. But most IR guys I know would see that as a sign that they need to improve their referral base or gain access to additional time in the suite, rather than a fun opportunity to exercise their stroke chops. But we all make our own choices. You certainly aren't wrong to try to strike a balance with either stroke or ICU as you prefer.