In this paper, we introduce an experimental study to characterize the dependence of the proximity effects encountered in parallel microfabrication based on the use of DOEs in various experimental conditions. By proximity effects we more precisely mean: any local changes in the 2PP threshold linked to the presence of other light spots in the vicinity of a studied light spot (spatial proximity effects) or to any previous exposure of the resist -whether leading to polymerization or not -by spots scanned across the same plot area (temporal proximity effects). This approach has been combined with a phenomenological computer model allowing us to demonstrate the effect of point spread function (PSF) overlap and diffusion processes, partially quantifying the range of the effect under specific conditions. We thus highlight three distinct regimes depending on the write spot separation: i/ small inter-structure spacings where light spot overlap effects outside the focal plane (Talbot-like effects) make any attempt of parallel twophoton DLW extremely challenging; ii/ intermediate spacings in which diffusion (for example of radicals) plays an important role in creating "crosstalk" between exposed spots (proximity effects) and undesired overpolymerization that can, however, be overcome; iii/ large spacings where no particular difficulties arise. Ultimately, we show that it is possible to circumvent these proximity effects using larger separations between spots.