With M and K track, you can always do some "adjustments" to make the tracks go together in a way that looks adequately ok..   With C-track, this is a bit more difficult due to the "snap" design that locks the tracks together, and this requires more exactness in track lengths already at the planning stage. 

So, we have put together some tables of the possible lengths of C track combinations up to 1 m. 

Hope you might find these track combination tables useful...
 

Up to 300 mm

Between 300-400 mm

Between 400-500 mm

Between 500-600 mm

Between 600-700 mm

Between 700-800 mm

Between 800-900 mm

Between 900-1000 mm
 

A RTF-document download of the complete table is available on the download page on the site...