Frequency of stretching

Assuming lack of flexibility is the cause of the issue, how often and for how long should one stretch if they wish to overcome this problem within the shortest time period?
 
Im considering 2-3 times a day, 5 min hold per stretch. Also foam rolling 2-3 times a day. Would this be too often?

only IF the lack of flexibility is due to a 'tight' muscle should you use stretching.
If you wish to develop the length of a muscle you need to hold it in its longest position for at least 90 seconds.
Maintenance only stretching is 30-60 seconds.
3-4 times a day would be great and using a foam roller should help the process yes
may u ask why the rush?

Hi Rach you did comment on a post of mine about the problem I was having with a clunk by my knee. I did see someone a few years ago at a sports injury clinic and he did notice I had very short hamstrings and this could be causing the problem. He gave me a progressive method of stretching and said I should do it for 5 mins a day.
 
The reason for the rush is its preventing me from deadlifting and squatting (or training legs at all) and its something I feel is really holding me back. Im taking time away from the gym at the moment and using the time instead to lengthen my hamstrings.
 
 

I see yes I remember
One thing you might consider (if i didnt tell you already?) is if stretching doesnt help your hamstrings, that they may well not be 'tight' and in fact they could be going into a protective spasm to protect the sciatic nerve. If this is the case then stretching is NOT what you really want to be doing at this stage but nerve mobillisations instead.
So see how you get on and if you want to know more about the 'slump' technique to get your sciatic nerve moving then let me know.
 
One word of advice is dont try and rush it. i appreciate you are wanting to get back into training legs but it would be prudent to train smart too and take your time. strength will come back no problem and much better if you can address the cause of the problem