Which is better - 2 short or 1 long ?

I know a form of this question is asked regularly but may be this is a different spin on it.

Is it better to do 2 short runs or 1 longer one?

Case in point: yesterday evening I missed my interval session and only had time for a 30 min run. So my choice was (A) 30 mins easy on Thursday followed by another easy run (30-40 mins) Friday morning or (B) drop the Thursday run completely and do a longer (60 min) run on Friday morning.

I went with option A on the premise that it's better to get out every day if possible and it feels to me that the cumulative effect is actually greater from two short runs i.e. 5+5 > 10 This might not be true if it was an LSR but for shorter runs maybe.

I know you could say option C, do the intervals on Friday but my only choice was an early start and I can't hack the intervals at that time, yet.

I know in the long run it makes no real difference, just interested in what others think.