From my experience in Biochemistry and Nuerobiology (and I'm assuming most Biology and Chemistry fields).

Unfortunately, in the US, no it does not help in completing a PhD sooner.

Sometimes a masters is necessary for a person just to get into a PhD program, depending on the person's history and the program.

It would help if the PhD had some requirement of a certain level of understanding or even amount of research work, but instead a PhD tends to just require an amount of time as an indentured servant to your PI - and that amount of time doesn't change if you have a masters. Although, if you're clever and a good salesman maybe you can convince your PI and committee that your masters time should count toward your sentence/years of labor.

From my experience in Biochemistry and Neurobiology (and I'm assuming most Biology and Chemistry fields).

Unfortunately, in the US, no it does not help in completing a PhD sooner.

Sometimes a masters is necessary for a person just to get into a PhD program, depending on the person's history and the program.

It would help if the PhD had some requirement of a certain level of understanding or even amount of research work, but instead a PhD tends to just require an amount of time as an indentured servant to your PI - and that amount of time doesn't change if you have a masters. Although, if you're clever and a good salesman maybe you can convince your PI and committee that your masters time should count toward your sentence/years of labor.

Unfortunately, in the US, no it does not help in completing a PhD sooner.

Sometimes a masters is necessary for a person just to get into a PhD program, depending on the person's history and the program.

It would help if the PhD had some requirement of a certain level of understanding or even amount of research work, but instead a PhD tends to just require an amount of time as an indentured servant to your PI - and that amount of time doesn't change if you have a masters. Although, if you're clever and a good salesman maybe you can convince your PI and committee that your masters time should count toward your sentence/years of labor.

From my experience in Biochemistry and Nuerobiology (and I'm assuming most Biology and Chemistry fields).

Unfortunately, in the US, no it does not help in completing a PhD sooner.

Sometimes a masters is necessary for a person just to get into a PhD program, depending on the person's history and the program.

It would help if the PhD had some requirement of a certain level of understanding or even amount of research work, but instead a PhD tends to just require an amount of time as an indentured servant to your PI - and that amount of time doesn't change if you have a masters. Although, if you're clever and a good salesman maybe you can convince your PI and committee that your masters time should count toward your sentence/years of labor.