Re-using developer

[NathanAlexander]

Hi,
I'm using Ilford ID-11 to develop rolls of HP5 Plus (and a couple of Kodak T-max), all 400 ISO. I intended to re-use the liter of ID-11 for ten rolls, but after developing four rolls (two at a time in a two-reel tank) I accidentally dumped out the developer instead of pouring it back in the bottle.
So I now have 500ml of developer that has only been used to develop two rolls of film. It has been sitting in an opaque one-liter milk jug for several days now.
I have 6 more rolls I'd like to develop with my remaining 500ml of ID-11 (because I'll soon be moving somewhere I won't have to pay for shipping). If I did, because I will be using the same 500ml for 3 more two-reel tank batches, would I still add the regular 10% development time per roll? Or more, because the developer won't be being diluted with the half of the liter that doesn't get used?
Thanks for any help or advice you can offer!

 

[Kirep]

General advice from Hans Windisch (1955) of W655-fame this is the series 1 - 1.06 -1.13 - 1.19 - 1.27 - 1.35 - 1.43 - 1.51 - 1.60 - 1.69 - 1.79 - 1.89 - 2.0 these are MULTIPLIERS. you multiply first film time....

This is what he says about two films per tank : "same time development of two films: jump straight to the next multiplier pass one multiplier. 120 films equal to 36 exp 135, obviously 1 12 exp and one 24 exp 135 equals 1 36 exp...

 

[NathanAlexander]

Ok that's good to know, thanks.