Hacking has always been a hot issue and many people had mixed feelings on it. While I personally love the concept of hacking, I should agree that hacking on normal rounds is not very functional nowadays and is only causing several issues.

• The concept of rooms is heavily luck-based. Depending on one's luck, there may be 0 to several submissions that can be hacked, and it is unfair to give several hundreds of free points to those who get a jackpot room. Even for the ones who submitted a wrong solution that passes pretests, it requires luck for them to be hacked by someone else so that they can realize that the solution was wrong and resubmit.
• Image blurring is not effective. Although by the rules using OCRs to convert the images to texts is prohibited, there is no way to know if one is using them or not. In the old days, even if someone uses them we may have thought that it won't be very accurate, but nowadays OCRs are just too good and only the honest people who don't use them gets disadvantaged.
• Recent trend is to have strong pretests. Especially with the multi-test problem formats, it is usually very unlikely to find any hackable solution in a single room.
• It is abused for cheating. As it has been brought up many many times, the ones who distribute solutions to others don't use their own solution; instead, they open others' codes and share them instead. This way it is harder to detect who originally started to spread them, and sometimes the original author is mistakenly flagged as sharing their code online.

For these reasons, I propose that we completely remove normal hacks during rounds, and apply post-contest open hacks to all rated rounds, along with a few changes.

• Assign only a few (1-3) hours to open hacking. I hope this phase to be somewhat concentrated and be an active period where people discuss about hackable solutions and try to contribute to strengthening the tests. People don't need to wait for another full day to have their ratings updated.
• Treat open hacking phase seriously. Just like during the contest, any issue that occurs during this phase (queue delay, wrong validator/checker, unexpected verdict) must require immediate action by the writers/coordinators and be announced properly. If this heavily affected the phase, extending the phase must be an option.
• (Optional) Like we did on very old Educational/Div. 3 rounds, mention the best hackers in the announcement. An example can be found here.

These can all be applied to current Educational/Div. 3&4 rounds as well. I hope that this will also lighten up the burden of the problemsetters to prepare the strongest tests possible.