In a nutshell, Scrum is explained like so (emphasis mine):
- A Product Owner orders the work for a complex problem into a Product Backlog.
- The Scrum Team turns a selection of the work into an Increment of value during a Sprint.
- The Scrum Team and its stakeholders inspect the results and adjust for the next Sprint.
The idea with running sprints is that you use them as a minimum cadence for delivering working software, or at least have something at the end of the sprint useful to inspect. This is the product Increment (or a bunch of increments if, for example, you deliver more throughout the sprint by using practices like Continuous Integration/Deployment/Delivery). You then use the increment(s) to adapt your strategy and decide on what to work next, or what's important next. You also use the opportunity to do a retrospective to see how you can also adapt and improve the way you are working.
The longer you wait to provide something useful, the longer the inspect and adapt loops, and the more problems or risks that can manifest themselves before you can adapt.
I've seen many companies that develop software and deliver value using an old fashioned approach, like sticking things together into milestones every quarter (at best) using mini-waterfalls, with Gantt charts laying out work in horizontal layers, with a final stage for integrating all the work, etc., but they expect their teams to do Scrum at the same time. What happens is that they just make developers work in sprints, with a bunch of meetings that frustrate everyone because they are empty of meaning (since work is still done in the same old way but differently), but the meetings need to be held because Scrum says so. That is not Scrum.
If you want to do Scrum, then try to follow its rules.
If you are doing something else which works for you, and you are not bothered by the risks or problems that can occur during a large development effort with a long feedback loop to match, then that's fine too. Just don't call it Scrum and don't force people to participate in ceremonies that don't fully make sense on their own, without the other pieces fitting together also.