Except for many years ago, when I worked for the State of Alabama Bridge Bureau, no one ever checked any of my calculations, regardless of the size of the office. Drawings we generate often get a reasonably good going over by the client (I do a lot of industrial work, and work for the military). That helps a lot. But no one looks over my shoulder on calculations. The only recent exception to this was the geotechnical expert for NAVFAC, who helped check my soil stiffness and foundation calculations for an octagonal wind turbine footing. As you suggest above: be really, really careful, and conservative, and then let it sit for a while, and then come back to it again (if the time available allows such a luxury). I hope you find a better answer for this than I have thus far.
Dave
Thaidavid