Venus has a very well observed and predictable orbit. From the perspective of all but the most demanding, its orbit is simple. An equation in Astronomical Algorithms that assumes an unperturbed elliptical orbit predicts the perihelion and aphelion times with an error of a few hours.Meeus (1998) pp 269-270 Using orbital elements to calculate those distances agrees to actual averages to at least five significant figures. Formulas for computing position straight from orbital elements typically do not provide or need corrections for the effects of other planets.see, for example, Simon et al. (1994) p 681
