Hi @S_Hickey , you can have a look at this post of mine, which may have something to do with my title that @Phil_Seeman refers to. 
This post should hopefully help you with your implementation strategy in general, but have a look at section 5 in particular, on Portfolios and Workload. There havenât been any reports on the limit of how many portfolios can be nested within a portfolio, depending on the total sum of projects, whether they count towards the total amount of projects. It would be an interesting exercise for a rainy day, and Iâd rather avoid speculating until then.
However, you mention the â250 project limitâ within a portfolio, actually it is 500 projects within a portfolio, but up to 250 projects for the Workload feature to function.
Another issue to note, if you are looking into using the Workload feature, then I would avoid nesting portfolios altogether because the Workload feature (as well as Timeline view) is instantly disabled for the portfolio that contains another portfolio within it. This would only not be an issue if you do not need the Workload feature for your âmaster portfolioâ that would have nested portfolios within it. But you could overcome that scenario if you are on an Enterprise plan and use the Universal Workload feature instead.
PS: @Bastien_Siebman , @Arthur_BEGOU , @lpb , any experience with hitting such limits with nested portfolios?