BusyCal 3 (latest version: 3.1.4) has a much too wide minimum width for the To Do column which forces the width for the days in month view to be very narrow which then forces many entries to use more than one line.
I would be willing to pay for an upgrade from BusyCal 2 if that would get fixed but the developer has no interest to do this (I asked him to do this immediately after BusyCal 3.0.0 came out). He apparently thinks to know better than his users how wide the To Do column should be.
I therefore don't pay for an upgrade and stay with BusyCal 2.6.9 where the To Do column can be narrower (and the days wider). BusyCal 2.6.9 works very well in macOS 10.12 Sierra.
The 2 stars are for version 3 only; version 2 still deserves 5 stars.