How long can a Doctoral student dependent visa Holder stay outside UK

[arunopol]

I have a Doctoral Student (PhD student) visa and My wife has a D student partner visa. Is there any rule that she will have to stay in the UK for a certain period of time at a stretch?
She still doesn't have a career aligned job in the UK and hence has not moved to the UK and continues to work from India. She plans to visit every 6 months.
Will her dependent visa get cancelled If she is unable to stay at a stretch for 6 months in a 12 month period?

[sah10406]

Is there any rule that she will have to stay in the UK for a certain period of time at a stretch?

No.

Will her dependent visa get cancelled If she is unable to stay at a stretch for 6 months in a 12 month period?

No. Where are you getting "6 months in a 12 month period" from?

But separately from this, if she only plans on visiting the UK now and again why didn't she just apply for a Standard visitor visa? As it is, a Border Force Office could in theory decide she is on the wrong visa and cancel it under one of these paragraphs:

9.20.1. Entry clearance or permission held by a person may be cancelled where there has been such a change in circumstances since the entry clearance or permission was granted that it should be cancelled.

9.23.1. A person’s entry clearance or permission may be cancelled if they cease to meet the requirements of the rules under which the entry clearance or permission was granted.

It's unlikely, but it's always best to have a visa that reflects your exact purpose for being in the UK.

https://www.gov.uk/guidance/immigration ... or-refusal

[secret.simon]

Quite apart from the advice given by @sah10406 above, you may also want to think more long-term.

If the plan is to apply for British citizenship, there are absences requirements for the five/three years before the date of naturalisation/citizenship application as well as a requirement about being physically present in the UK at the start of the five/three years period before the date of naturalisation/citizenship application.

So long absences now can impact applications years down the line.