No they don't.
In the Public Sector there are rules that say if you are in a contract for more than 6 months, paying more than £200 per day then you have to provide evidence to the client that your Tax and NI payments are compliant with IR35, either inside or outside.
If you work in the same general location (whether in the Public or Private sectors) for more than 2 years then you can no-longer claim travel and subsistance costs. Location is very broad, so 12 months with one London Client followed by 18 Months with another London Client would be caught by this rule (30 months in one location). If the commute doesnt fundamentally change (Next Client is in Leeds for example) then the rule applies.
Other than that there are no restrictions on how long you can contract with the same client, nor is length of engagement an indicator of your status under IR35.