Hello m_b_e_m_ch_p_tt,
Thanks for contacting us with your question.
Unfortunately we do not have a such option and it is not possible to achieve something like that from an API level. By default chart's plot try to fill whole available space. In effect, when there are only few nodes, they are thick. If you don't like that behaviour and you would like to see an option which would allow to set max thickness then I highly encourage you to leave your feedback on Highcharts User Voice or create freature request ticket github.
User Voice: https://highcharts.uservoice.com/forums ... script-api
Github:https://github.com/highcharts/highcharts/issues
Alternatively you could try to extend a function that is responsible for calculating node width. More about it you can read here:
https://www.highcharts.com/docs/extendi ... highcharts
Let me know if you have any further questions!
Best regards!