i like yearly updates at the same time, even if its just a processor why not? there is a certain group of people who like latest and greatest (myself included). i don't think it makes sense to wait for a big update to update it, otherwise it may never happen, and consumers end up buying 2 year old tech (sound familiar?)
the best time to put out a new ipad is nov'ish like when the 12.9 ipad pro came out, then you can include the lastest processor...the only downside to a new ipad pro coming out now is they might not include the A11X because they don't want to rein on the iphone parade. Which i don't get that either, its no secret the new iphone will have the A11 and it doesn't make it any slower to release it in an ipad first, and not going to make someone NOT buy an iphone...