When to stop sparging

[MARMITE]

I was very interested in the correction tables for 15.6C hydrometers in the brewing equipment section. I have always stopped sparging at about 1005 to avoid extraction of tannins etc. but hadn't realised just how much of an adjustment needs to be made for high temperatures. If my reading of 1005 is taken at the exit to the mash tun and the temp is say 70C the true gravity is likely to be about 1027. Am I stopping sparging too early and should I be waiting until the gravity on the hydrometer is nearer 980 or so? I haven't got time to cool the wort down between each reading as I find the gravity drops very quickly towards the end of sparging.