Can we please have the option of setting the Holding Time to zero in aircraft profiles. At the moment, the minimum allowable is 10min.

Not all flights require holding.

Thanks

Like plume_tray, I think the terminology is misleading.  It looks like you're trying to incorporate a reserve, so call it Reserve Fuel or Final Reserve Fuel is appropriate.  But it's not for holding.  Holding fuel is something different, and is rarely required.  

T‌he standard buckets (used in CAT) are:

T‌axi Fuel
T‌rip Fuel (take-off to destination)
A‌lternate Fuel ‌‌(destination to furthest alternate)
C‌ontingency Fuel (typically a % of trip)
E‌xtra Fuel (for anticipated delays, which may include holding)
D‌iscretionary Fuel (loaded at the captain's discretion)
F‌inal Reserve Fuel (fixed at 30 mins for CAT turbine, soon to have more flexibility in NCO)

(‌There's also Additional Fuel, which accounts for an engine failure or depressurisation at a critical point, but is not likely to be relevant for most GA.)‌