Frequent visit on 5 years UK visitor visa

[AJ001]

My mom holds a UK 5 years visitor visa and Canadan 10 years parent visa and Pakistan passport holder. Before having 5 years visa, she had 6 months visa twice and visited for 4 months each time, and then she applied for 5 years visitor visa. On 5 years visitor visa, she came to use it twice within a year. (Once for 5 months and then 3 months in Pakistan and then 2 months in UK again). Now she wants to come to UK again for 5 months, and she finished her UK visit 2 months ago. Her 5-year visa expires in 2030. My questions are

1 - Will she not stay more than 6 months in UK within the timeframe of 12 months?
2 - Will frequent short + long travels cause an issue for her at airport immigration desk, leading to refusal of entry?
3 - I am sure these frequent travels will cause issues in her future visa application
4 - One long stay within a year is more sensible option or multiple short stays in a year ?

Thank you

[CR001]

She should not be spending more time in the UK than her home country. She appears to be doing exactly this, more time in the UK than her home country.

Frequent visits and long stays in a relatively short timeframe risks her visa being cancelled if it appears she is reading in the UK under the guide of a tourist visa.