Bug report

Bug summary

I noticed that when using eventplot to plot a big number of events, the plot doesn't shows all the binary data available, and is needed to increase the linelenghts parameter to increase the number of lines in the plot.

Code for reproduction

import matplotlib.pyplot as plt
import numpy as np

#simulate some raster (is needed for the number of events to be high
#I noticed missing lines for n_events > 200)
data = [np.random.random(np.random.randint(10)) for i in range(500)]
fig,axes = plt.subplots(2)
axes[0].eventplot(data,linelength = 1)
axes[1].eventplot(data,linelength = 2)

Actual outcome

Expected outcome
I would expect to have all the binary data plotted in the figure

Matplotlib version

• Operating system: Arch Linux
• Matplotlib version (import matplotlib; print(matplotlib.__version__)): 3.3.2
• Matplotlib backend (print(matplotlib.get_backend())):module://ipykernel.pylab.backend_inline
• Python version: 3.8.5