No. Although it is approximately equal in volume, it varies between different men and even in the same man. For example, factors such as days of abstinence may cause changes in seminal volume.
The fact that one day the ejaculate is of low volume should not be cause for concern.
Read the full article on: What Is the Normal Semen Volume in Males? ( 85).

Rebeca Reus
BSc, MSc
Degree in Human Biology (Biochemistry) from the Pompeu Fabra University (UPF). Official Master's Degree in Clinical Analysis Laboratory from the UPF and Master’s Degree about the Theoretical Basis and Laboratory Procedures in Assisted Reproduction from the University of Valencia (UV).