No.
The initial plan was based on the earlier variants. It was already known that if something new came along, or new evidence about how long they lasted, things would have to change. It's not just sprung on us - Omicron has thrown a serious spanner in the works. The third booster is thought to protect reasonably well against that.
Without Omicron, the previous two would likely have been enough for many people, at least for some more time, as even with somewhat waning protection, they were doing an OK job at containing the serious cases. They were adding boosters for the older or more vulnerable, as protection lessened. Now, they need to do it asap, for everyone, because that's the only way to stop Omicron.
They could do more research on the absolute best combination and timing of the doses, but at the moment, that would just mean a lot more cases and deaths in the meantime. So if 3 months isn't the ideal gap before a booster, they could adjust that for the future, but for the moment, it's better than not being boosted.
Hopefully there won't be a new variant that escapes vaccines, and they are working on newer vaccines and treatments that are hoped to be more effective against mutations, so that it won't need to be an ongoing process - or if it does, more like a once a year flu shot. Once the number of cases in circulation goes down to a manageable number, then it won't be as vital for everyone to be boosted all the time either, as the chances of coming into contact will be rarer, and there will be more of an underlying immunity by then too.