Al Svanberg did tests, it is 30-35% more CL from minute one. Or ~15% more for every half. What is the average CL on default mixed/off orders, like 20-25% if I'm not mistaken? I don't remember exactly, lol xD
So it is 3-4% of condition for every half or twice this amount for the whole match on High pressing. Equivalent of two green packs, approximately, if you summarise CL for the whole team. For every half played with high pressing.