When you utilize p_sequencer in a sequence, you are requiring that sequence to run on a specific sequencer type. By not using p_sequencer, your sequences are more portable and can be utilized on any sequencer that is type’d appropriately (i.e. creates the appropriate sequence_item).
If your lane_model is interface specific, then I would include it as part of the Agent’s configuration object. Your sequence would have a handle to the Agent’s configuration object that would be assigned when the sequence is created. The sequence can then make direct use of the lane_model from the configuration object.