On proving of a will in 1866 in Ramsbury England, the executors state 'Effects under thirty five thousand pounds'. Was this a general figure for wills or would this represent a rough net worth?
When a will was submitted for probate, the executors would assign a category indicating the upper limit of its value. In this case, they asserted that the worth of the estate was not more than 35000 pounds.
In order to get a sense of what that means relative to the rest of the community of the day, you need to view a selection of documents from the same (approximate) time and place to see the categories applied to other people's estates. In particular, you need to know the next smaller category (less than 35k).
A very unscientific sample (of one family name for 1866) contained six estates (one under 100, two under 200, one under 300, one under 600 and one under 2000 pounds). In that company, your example stands out like the wealth of Croesus.
The other way of looking at this is to try to find the equivalent in post-2000 pounds. The National Archives suggest more than 1.5 million.
It's hard to say for sure without knowing more - for example what jurisdiction the will was proved in.
Given that thirty five thousand pounds was a pretty substantial sum of money in 1866 however my guess would be that it just means it was somewhere between zero and that amount.
Most likely some extra rules or taxes kicked in for estates valued above that level and that statement is simply saying that they do not apply to this will.