If you can get DBS to stick (and you use something to tutor for it), then you are looking at 1+N cards, where N is the number of DBS’s installed. The runner similarly has an access rate of base 1 on R&D which they will try to increase and might increase up to or past the number of DBS’s you get to stick, but if they don’t have R&D interface or if you can get enough DBS to stick that your “access” rate is higher, you are more likely to access a card than your opponent. If your deck is bigger, your opponent’s chances to access that card become even lower than your chance to access the card. If the card is astroscript pilot program, then this might be worth it.
Really, I think all this means is that a runner should be trashing DBS on sight, but that if they weren’t doing that for some reason then a larger deck may lead to a longer game, but that DBS might actually increase your chances for success by reducing your chance for failure.