Problem :
Thanks to the headsup* by 
we came to know that big power dolphins and whales can deplete their power 100% by upvoting their own content and then turn around and delegate 100% of their depleted power to their second account and deplete the power again 100% by upvoting their own content. Then they wait 7 days and do it again at a profit of 150% of what they would get upvoting 10 posts per day at 100% power thus gaming the ecosphere.
Solutions
Proposal 1.
Calendar Approach (Purgatory)
One proposal was to extend the delegated power return time to 11 days from the current 7 day "Purgatory", which solves the financial issue by making it unprofitable, but could undermine usage of delegation by tying up delegated power longer than desired or required. Even 7 days seems like a long time to begin with.
Proposal 2.
There are other ways to curtail this problem that need not negatively impact SP delegation. Here are some possible options.
A. Handcuffs.
Should you be able to delegate power that is drained or should you only be able to delegated unused power? I think we should be able to delegate drained power. Restricting this might come across to lenders as too rigid and inconvenient causing less power to be delegated by even legitimate power sharers.
B. Magic Show.
Should power delegated in a drained state not start to recharge for the lender until it returns back to the lender after 7 days? This sounds better than (A.) but it still doesn't seem fair that drained power magically and instantly recharges for use by the borrower.
C. NiCad Battery.
Should drained delegated power need to be recharged by the borrower before it is usable by the borrower? I call this the NiCad Battery Model and I like this the best as it comes across as the most flexible, fair and logical solution. IRL if you loan me a depleted battery I need to recharge it to use it. It might involve assigning a depletion /recharge state or clock to each unit/block/contract of power that is independent of lender/borrower like the timers on equipment in games like Mobile Strike. Coders need to consider if that is going to be feasibly added to the blockchain.
See our development discussion forum here
https://discord.gg/9SQvxJT
Hope this helps.
P.S. I opened an issue report on Github for this and it is open for comment at https://github.com/steemit/steemit-docs/issues/6