1 meter speaker cables

"Am I overthinking this?"

Of course you are, but the alternative is worse.

Nothing good happens when you underthionk.

My feelings are multiple. I do think speaker and interconnects matter more than the math about inductance, capacitance and resistance would lead us to believe.

I also think they are the least cost effective "tone controls" money can buy.

To get back to your question, longer cables should create more of whatever tonal effect they cause, but why? Your speaker choices and preamp are much better places to spend more money in finding the right combination of attributes you are looking for. Speaker cables are not IMHO a benefit, but rather a necessary evil for most of us who have passive speakers.

If you have monoblocks for instance, put them as close to the speaker as possible to shorten the speaker cables, at the expense of longer interconnects.

1. At 1m length do the differences that may be present at longer lengths of say 2.5m become less noticeable?

Obviously the shorter the cable the less resistance, but there is plenty more to a speaker cables function than resistance. 

If you agree with Transparent cable's philosophy every length needs its own specific network box to adjust capacitance, inductance etc. for maximizing sound quality: 

"The balance of a cable's electrical properties changes according to the length of the cable. Transparent not only optimizes for the cable design itself, it optimizes every network for every length of cable to meet that specific product's design criteria. Regardless of the length of cable required for a particular system layout, the performance will meet the standard for that cable design. With Transparent, there are no compromises for needing a longer or shorter cable."

Their stock cables start at 8 feet, but they do make custom lengths. Not sure what they say if someone wanted to order some 3 foot speaker cables for monoblocks, I am sure someone must have them, or do they suggest only longer lengths are possible? Of course these may be beyond your budget. 

Pierre at Mapleshade always said 8 feet is ideal...not more and not less... 

I used 1M long speaker cables for years.  In my experience, and in my system, I could indeed hear differences in 1M long speaker cables. I actually have a variety of 1M speaker cables that I have compared and the sonic comparisons between given types of cables are similar to what I hear when comparing the same types of cables in my current set-up, where speaker cables are 2 to 2.5M long. 

One way to reduce the effects of resistance, capacitance, and inductance in a cable is to reduce the length of the cable.  Therefore, the sonic effect of 1M long speaker cables should theoretically be less than for longer speaker cables, although the difference may not be easily discernable.