At the same time, you can argue that these different tactics reflect the needs of the Borg at any given time. A Borg cube on its own, in a generally scavenging mode, may have the luxury of growing children as foot soldiers for the Collective. While the Borg in a crisis situation -- like in First Contact -- must resort to extreme tactics given the situation.Christopher said:
To be fair to Arnold and Roddenberry, at that time, the concept of assimilation wasn't integral to the Borg yet. "Q Who" suggested that drones were incubated from an embryonic stage as drones and never had any other identity. BoBW showed Picard getting assimilated, but presented it as a change in Borg tactics. It was consistently stated that the Borg assimilated civilizations and technologies, with no interest in individuals. Even after Vendetta, in "I, Borg," Geordi was able to stand by safely while the Borg returned to retrieve Hugh, because the Borg weren't interested in individuals as a rule. The concept of assimilation as a normative process didn't come along onscreen until FC, where the Borg were reinterpreted into something more zombie/vampire-like, something that consumed people rather than disinterestedly running over them. And of course that was developed far further in VGR and became the accepted Borg paradigm from then on.
Assimilation of someone like Reannon Bonadventure makes sense; humans were a new race to the Borg, and bringing her into the Collective and accessing her mind would give the Collective access to her memories and knowledge. Why interrogate, when the Collective can get what they need and add a new drone to the Collective?
I don't know, I think Locutus' conversation with Worf in "Best of Both Worlds II" is pretty suggestive that mass assimilation of new races is the norm.So Vendetta pretty much anticipated the idea of the Borg assimilating people as a pattern, but at the time, it hadn't been clearly established in canon.
After that? Borg population growth may well be a combination of lab grown bodies and assimilated races.