We study a primitive vehicle routing-type problem in which a fleet of $n$ unit speed robots start from a point within a non-obtuse triangle $\Delta$, where $n \in \{1,2,3\}$. The goal is to design robots' trajectories so as to visit all edges of the triangle with the smallest visitation time makespan. We begin our study by introducing a framework for subdividing $\Delta$ into regions with respect to the type of optimal trajectory that each point $P$ admits, pertaining to the order that edges are visited and to how the cost of the minimum makespan $R_n(P)$ is determined, for $n\in \{1,2,3\}$. These subdivisions are the starting points for our main result, which is to study makespan trade-offs with respect to the size of the fleet. In particular, we define $\mathcal R_{n,m} (\Delta)= \max_{P \in \Delta} R_n(P)/R_m(P)$, and we prove that, over all non-obtuse triangles $\Delta$: (i) $\mathcal R_{1,3}(\Delta)$ ranges from $\sqrt{10}$ to $4$, (ii) $\mathcal R_{2,3}(\Delta)$ ranges from $\sqrt{2}$ to $2$, and (iii) $\mathcal R_{1,2}(\Delta)$ ranges from $5/2$ to $3$. In every case, we pinpoint the starting points within every triangle $\Delta$ that maximize $\mathcal R_{n,m} (\Delta)$, as well as we identify the triangles that determine all $\inf_\Delta \mathcal R_{n,m}(\Delta)$ and $\sup_\Delta \mathcal R_{n,m}(\Delta)$ over the set of non-obtuse triangles.

https://link.springer.com/chapter/10.1007/978-3-030-79987-8_24