Yes, I would agree. Please bear in mind that my response is based on systems from the 1980s. I would normally leave this to someone closer to reality than myself, but as a distraction might be beneficial I will give it a go. We used what was/is termed a wireline recovery system. The main rod line would be withdrawn to the required distance to allow the top section or sections to be removed. A "spear" which is attached to the wireline (which is on a winch drum of its own) is then dropped down the rod string (line) until it finally latches onto a mechanism to attach itself to the core tube and at the same time release the latch of the core tube from the inside of the drilling barrel. You can tell when the spear latches by grabbing the rods with a pair of stillsons and a putting your ear firmly against them. You can hear the "click" through the stillsons as the spear lands. The wireline is then retrieved bringing the spear and the core tube with it. The spear is unhooked and the core tube emptied of the beautiful 6 metres of solid nickel sulphide "Usually" the core tube can be simply simply be inserted back into the rod string unattached letting it "parachute" back to the barrel at the bottom. The resetting or "latching" in place can be heard once again through the stillsons as described above. So, yes it is not necessary to remove the entire rod line each time you want or need to remove the core tube.
Hope this is detailed enough and simple enough to be understood and that the system is still similar.
"Usually" the core tube can be simply simply be inserted back into the rod string unattached letting it "parachute" back to the barrel at the bottom.
