Probably getting a bit off topic, but it really depends on the network you're using, the equipment, distance to your control stations, etc. We have some GCPs that are GPSed for multiple hours because that's what is required to hit our job specifications. The control portion is easily the longest and most difficult part of any of our aerial mapping projects; flying is the easy part.
On a typical job, we have 4 rover methods and it'll depend on if we're within cell range to a correction network (VRS), want to use a satellite correction (RTX), want to use RTK to a radio base, or post-process to a non-radio base (PPK). Then we check-in to a minimum of 5 existing monuments, which may be several miles from the project site and may or may not still exist, so it's a bit of an easter egg hunt. Then we start shooting the GCPs and gathering check shots. We'll usually GPS our GCPs for 5-10 minutes (depending on the setup used) and hit our topo checkshots for up to 3 minutes (sometimes longer). After the field, everything is run through Trimble Business Center and there's usually some arguing about which monuments to hold and which base stations to use. The grid coordinates are converted to ground coordinates, but the scale factor depends on the specific project that we're doing. Then... we have our final locations for loading into Pix or PhotoScan.
So, when there's a product that gives us reliable results by placing them on the ground and picking them back up after 45 minutes, it's pretty appealing. Our biggest issue is that we like to have topo check points for accuracy calculations, so we already have to have a rover in the field. But if we have a less demanding project or only volume calcs, I'd like a set of APs to use for simplicity sake.