I say, and with God's help: Fasting the white days is recommended, and it is also recommended to fast them consecutively. It is recommended to fast on Friday even if alone; it is even more so if it is preceded or followed by another day. As for Saturday, it is disliked to single it out for fasting out of a desire to avoid resembling the Jews in honoring it. However, fasting it with other days is not disliked. And God knows best.