Repository of knowledge about input lag in gaming

I was recently playing Hollow Knight on the PS4 console. Mostly it was ok, but some portions of boss battles just felt downright unfair.

My original setup was to route the HDMI from the console to my AV receiver, then to an HDMI splitter (to strip hdcp), then to my 'gaming, very-low-input-lag' projector (rated at somewhere between 5-15ms input lag). It occurred to me that the difficulty may have been due to extra input lag caused by the receiver, so I tried an experiment, changing the connection order with the exact same components.

So this time I went from console, then to HDMI splitter, with its two outputs going to projector (for video) and AV receiver (for audio).

The difference was like night and day. Suddenly those battles that were 'almost unfair' went to 'almost trivially easy'. My best estimates for the amount of input lag the receiver was introducing was around 125-175 ms range. Pretty wild how much of a difference that made.

On a related, but different note - it reminded me of a concept I've purposely tried to implement it similar domains, that is: training with systematic disadvantages. In this case, the extra input lag acted as a systematic disadvantage that forced me to become hyper-responsive in order to stand a chance at succeeding. Additionally, it caused the viable response window to enemy actions to become short enough that specifically telegraphed moves were such that I needed to treat them as almost completely random, and adjust my response accordingly. In other cases, (especially in soulsborne games,) I specifically never invest skill points into raising my health in order to force myself to become better at the combat dynamics, and simply never getting hit, rather than allowing for health as a 'mess up meter'. Which generally allows for 'taking off the training weights' if ever needed,once a suitable level of mastery has been attained.

Does anyone else here have other examples of utilizing purposeful systematic disadvantages in order to improve one's mastery of a thing? Would especially love to hear any examples outside of gaming too, perhaps in career things/tech/etc.