I would like to run the following model: $Y_{ij}=\beta_0+\beta_1 X_{ij}+ f(controls) + e_{ij}$ where observations are collected from several individuals ($i\in[1,N]$) following several events ($j\in[1,E]$). Moreover, for each individual $i$, I have $X_{i1}=X_{i2}=\cdots=X_{iE}$.
As a concrete example suppose that $Y$ is an individual's approval rating of a politician recorded after each public speech of that politician and $X$ is the age of the individual. Also suppose that the data was collected over the course of a short period such that the age of each individual was constant.