Do you have to donate on the days you did before

You are supposed to..BUT you can change them if you skip a week. You can only donate twice a week so .. let's say you are going Tues and Thursdays and you go on Tues and they check you and say that your iron is too low, now you will have to go home, eat some spinach or some other high in iron food or supplement and go back the next day, if you are tested have have enough iron on Wednesday, then you will now go on Wed/Friday or maybe Wed/Saturday. If you decide there days you are going aren't working out, skip a week and start on a different day. In my area, the 'week' with them starts on Monday so (for example) you could go Mon/Wed, Mon/Friday or Tue/Thursday or even Tues/Friday or even Tues/Sunday..etc. you just cant go 2 days in a row or more than 2 times within 7 days. Its kind of confusing at first, but I eventually figured it out send took my time here to try to explain because they're really are a lot of options once you figure it out.

Yes