We (well, more specifically, I) started working odometry the summer between Nothing but Net and Starstruck (not actually knowing the term odometry hence why all our old stuff refers to it as position tracking and why we didn’t use one of the many implementations that came before us). Soon after that, @nickmertin joined and started helping me with it and we had an xdrive based implementation ready for the first competition, and a tank drive version ready for worlds.
Once I graduated at the end of starstruck, Nick took over the project and further refined it (rewriting most of the movement algorithms) into what you saw at ITZ worlds. However, throughout that year, Nick worked with at least two other members of the team so they could learn to program and take over when he graduated.
My point is, while you can get away with a single programmer, multiple people collaborating allows for discussion about how to do things and multiple different opinions which will inevitably leave you off with a better end result. You also always want to make sure to have someone to take the place of any graduating members (this goes for all roles on a team) if you want your team to continue to exist into the future.