While generically It would be acceptable to run in one conduit, There are many situations that would make such not advisable and maybe even not allowed. The limited information contained in OP post as well as on image of plans really has insufficient to give a definitive yes or no to your question.
Information such as: Are the 3 circuits coming from a single trough box or already in separate runs? Are these circuits generated from different sources characteristics or different panels? You mention using nipples to connect 3 boxes, would the enclosures involved create a fill issue with the pass through conductors and any respective devises installed? If coming down into a typical handy box (used a lot to give a lower profile and rounded edges) and switch or receptacle, box fill become a real issue for pass through.
