Is it recommended to use this to seal butt end joints in exterior wooden 5/4" trim? square butt ends? angled butt ends like 45 degree etc?

The QUAD MAX is not recommended for use in joints too small to accommodate enough sealant to withstand normal expansion /contraction. Joints less than ¼ inch generally fall into this category. This is not to say you cannot do this application but with the understanding these types of joints will require frequent maintenance at some point. This is generally true of all caulks and sealants when used in small joints. If trim was installed properly there should be no need to use a sealant or caulk in these kinds of joints

The QUAD MAX is not recommended for use in joints too small to accommodate enough sealant to withstand normal expansion /contraction. Joints less than ¼ inch generally fall into this category. This is not to say you cannot do this application but with the understanding these types of joints will require frequent maintenance at some point. This is generally true of all caulks and sealants when used in small joints. If trim was installed properly there should be no need to use a sealant or caulk in these kinds of joints