Not sure when you lived here but Germany does not require you to leave the country to renew the document that lets you re-enter¹, same as rest of Schengen. Renewal frequency is also 4 years for "EU Blue Card" holders (STEM workers).
¹: residence permit card in case of schengen, visa in case of "non-immigrants" in US.
¹: residence permit card in case of schengen, visa in case of "non-immigrants" in US.