I never bother to change my wing angle unless i have taken on some damage, or im actually lacking downforce in every part of the track, i think its more important to get other setups correct (such as toe and camper) than just the wing angle, and if im honest, i notice hardly any difference between + and - during races. I think its more important to just concentrate and focus on your apexes and exits, than to actually fiddle with settings, and as i am a PS3 player, pressing left,right,up and left,right,down just to change a wing angle, is one hell of an arse about and usually makes me loose concentration. The only time where i would consider changing angles during a lap, is when there is a big difference between the downforce required for each sector. For example, Spa, where the 1st and 3rd sector are high speed zones, and the 2nd sector is technical and needs downforce, i may change the wing to + for that sometimes. But as for changing angles corner to corner and straight to straight, i think thats overkill and an easy way of making mistakes due to lack of consentration.