I definitely think you should try to do a bit of Bio every day because it's easy to forget since it's mostly rote memorization. I haven't taken the DAT, but I can attest that studying bio every day has really helped me retain information and I've been averaging 20-21 on DAT Qvault and havent't even finished all of Cliff's yet. So yes, you should try to do more than one subject per day, but in large blocks of time. ex. 3 hrs bio + 3 hours chem
~ 2 weeks ago I was ranging 17-18 on Bootcamp PAT. Since then, I bought CDP and have been doing 1 test/day + generators and my scores have steadily started climbing. I took another Bootcamp PAT and CDP today and got a 21 and 25 respectively.
Unlike the other sections, PAT is something you have to practice daily to get good at it. Before these two weeks I'd immerse myself in PAT, but it only turned out to be frustrating. You should first perfect hole punch and cubes with generators, then start taking FL tests to mimic the test.
Good luck!