We rely on a few different services to provide the imagery used in the TNMCorps editor. Those imagery service providers refresh the imagery either quarterly, annually, or even every 3 years. If you're inquiring about Alaska imagery specifically, is a special case and many areas do not get updated on a regular basis due, in part, to a short acquisition season and predominance of clouds. [The National Map basemap site][1] states that "The National Map program is working on acquisition of high resolution orthoimagery (HRO) for Alaska. Most of the new Alaska imagery data will not be available in this service due to license restrictions."
This statement refers to the image service used in the TNMCorps editor. This license restriction may change in the future but there is not a timeline when that would happen.
Feel free to contact us directly at nationalmapcorps@usgs.gov with additional questions.
[1]: https://basemap.nationalmap.gov/arcgis/rest/services/USGSImageryTopo/MapServer
