In the Alien franchise androids have played an important role in the story line, from Ash through to David and Walter. However, is it known how common androids are? The names Ash through to Walter suggest only 23 androids in use? Are androids so expensive that they are only used sparingly or are they made use of only in special occasions?
By 2179, when Aliens is set, it appears that androids are ubiquitous. When Ripley is shocked at the revelation that Bishop isn't human, Burke is visibly confused, noting, "It's just common practice. We always have a synthetic on board." This would seem to indicate that any Company vessel will always include an android among the crew complement.
Ripley's surprise here, along with the Nostromo crew's reaction to Ash being revealed as a robot, indicates this was by no means common practice in 2122, when Alien is set. Their shock seems to demonstrate that they're aware androids exist, but they would not normally expect to see one on a routine ore-hauling job.
This would seem to be contradicted by the prequels, as both Prometheus and Alien: Covenant, both set around 2100, show crews fully aware that there is an android among the crew. It would appear that they're considered a necessary expense for colony ships, but not for freighters.
By the time of Alien: Resurrection, some 300 years later, androids are apparently extremely rare, having been outlawed after a failed uprising. Call's very existence was due to the fact that she wasn't actually built by humans, but rather by other synthetics.
The general timeline would therefore appear to be that synthetics are well known but uncommon in the early 2100s, hit their heyday around the late 2100s, and were nearly extinct by the late 24th century.