Summary plot comparing our median stacked fluxes (grey open circles) against multiple effects. From top to bottom: mean vs median stacking (Appendix A.1); contribution of MIRI detections (Appendix A.2); field-to-field variations (Appendix A.3); effect of photometric redshifts (Appendix A.4); effect of a broad redshift range (Appendix A.5). Details are given in the corresponding sub-sections.