# NMR spectrum of 3-hexylthiophene: why is the methyl group not a triplet?

I have an example spectrum, and it shows which peaks correspond to which H, but I don't understand why the spectrum looks like that

e.g. I would expect the peak at 0.88 to be a triplet based on the (n+1) rule, why is it such a large multiplet?

The reason why the terminal methyl group is not a simple triplet is because of strong coupling, which is the scenario whereby the coupling constant between two nuclei $J$ is comparable to the difference in resonance frequency $\Delta \nu$.