I've noticed that work units seem to be running somewhat longer compared to say a month or so ago.

My 750TI cards now are taking 26 to 30 hours to complete -- back in March these ran 20 to 23 hours. No change in the credit scheme.

I'm wondering if others have noticed this as well.

Think there may have been another thread about this somewhere.
In short, they are much longer but have, on average, more credit.

I thought I'd seen something about that.

I noticed in part because with the longer run time, the 30K bonus for completed tasks in 24 hours is just out of reach for my 750 TI cards.

I thought I'd seen something about that.

I noticed in part because with the longer run time, the 30K bonus for completed tasks in 24 hours is just out of reach for my 750 TI cards.

You could reduce your work buffer to 0.00 so you don't have them sitting on your machine for hours. BOINC Manager >TOOLS >Computing Preferences >Network Usage.

Then you could try slowly overclocking.

My GTX 650 Ti cards will now likely process only short tasks as the run time has gone over 34h for some long ones. I recently found two used GTX 650 Ti cards, one of which is installed, the other will follow. Long runs take about 18.5h with a GTX 660 Ti.

Correction: recently found two used GTX 660 Ti cards, one of which is installed, the other will follow.

From what I've read, the GTX 750ti might sustain overclocking of perhaps 5 to 10 per cent -- I figure I'll pass on that.