Chair conformation. Wedged lines vs no wedged lines?
Cyclohexane is often drawn as a regular hexagon even though its prevailing chair conformation is not planar.



Perspective diagrams are preferred when discussing conformation (since there is no other reasonable way to depict boat and chair forms) and acceptable when it is just desired to emphasize configuration. (For the depiction of carbohydrates and structurally related molecules, Haworth projections can be also preferred.)



The use of wedged and bold bonds in such perspective diagrams is discussed in Graphical Representation of Stereochemical Configuration (IUPAC Recommendations 2006):


  ST-3.3 Use of bold bonds to emphasize perspective
  
  Since perspective diagrams imply a single absolute configuration, it is not necessary to use solid wedged or bold bonds to emphasize that configuration further. In some cases, such bonds may help an inexperienced viewer to understand the perspective used. (…)




However, note that


  Only solid wedged and bold bonds should be used for the purpose of emphasizing perspective. Hashed wedged bonds and hashed unwedged bonds should not be used, either in isolation or in combination with bold bonds.