How do you guys and gals handle the issue of extra work/study/training time that sleep regulators and the sustenance power introduce? These options allow a player to get away with only 3 hours of sleep a day which gives a potential 4 to 5 extra hours to do something else in the day. The basic work day for training or building or whatever in SR is assumed to be 8 hours. So do these options allow you to work 1.5 times longer (12 hours instead of 8 hours)?

Not necessarily. Neither affect healing times, so they just let you stay awake longer - you still have the same physical and mental limits. So your wrist is still sore after fiddling with a microcircuit board, your brain is still fuzzy after reading those chapters on advanced thaumaturgy, etc. But either option would let you do a typical eight hours of work or training and still be able to do other things, such as taking care of a dependent or attending a social gathering.

depends on the table.

Most tables I have seen usually rule that you can only effectively train 8 hours out of a day, any excess doesn't really help toward advancement
Having the sleep regulator/sustenance power just means they can train and still do other stuff in their prolonged day. So if they were training their electronics skill and some extended working on the rigger's engine, they could get both tasks done.

In my game, I have a limit on how long that someone may effectively work/study/train during a day, with the limit based on the character's Willpower. I usually ballpark it as Willpower * 2 = hours of productivity on a single project in a single day.

If the character has a high Willpower then they have the mental stamina to maintain their focus and they can use the additional up-time provided by a sleep regulator to accelerate their work.

If they have a more normal Willpower then they burn out after 6-8 hours like most of us do and must spend their remaining waking hours doing something different. That "something different" may also be productive - like socializing with contacts - but it needs to differ from whatever the character's primary focus is at the time. Sendaz and Glyph both provide good examples.

For me, Sustenance is a different issue. I'm not as concerned with the time saved by not eating, but I do think Sustenance should be worth a lifestyle discount. If you're using the Advanced Lifestyle rules from 4E's Runner's Companion then I usually translate the discount as -1 LP from Necessities. At the Squatter level the discount is minimal (¥100/month, or ¥3/day) but at Middle (¥600/month, or ¥20/day) or higher lifestyles the discounts can add up.

I've usually set Sustenance's food discount at -10%, the same way something like the Suprathyroid increases the food aspect of lifestyle. Most characters seem to only get this power once they have something like the Suprathyroid and use it to directly counter the lifestyle cost increase.

I like the Willpower idea for how long someone can perform a given task though perhaps a test would work as well so if you don't happen to have a 5 or 6 Willpower there is still a chance you can do something beyond the 6-8 hour time frame. Need to decide if that is worth the extra paperwork though. Simple may be better and just straight up use your method.

Thanks for the ideas everyone.