I believe that red lines don't need to be the same in every difficulty and in certain cases that requirement is detrimental or restrictive for no real purpose. This proposal aims to reword the timing rule to specify that the general timing of the map must be similar but can vary within reason to meet the needs of the specific difficulty being timed. This can avoid situations like repeat sliders being nearly unusable on low difficulties in complex-timing sections, certain game modes being more or less stringent than others, or difficulties all being made to map the same layer of a song when timing may be slightly different between layers and mapping different layers would feel more natural.
I don't believe there's any mechanical restriction on different timing either so shouldn't be an implementation issue.
I don't believe there's any mechanical restriction on different timing either so shouldn't be an implementation issue.