Normal SOP is to arm the spoilers for auto deployment. The auto function will occur "On the ground, the Speedbrake lever stop retracts allowing the Speedbrake lever
to be moved fully aft to UP
position. All six spoiler panels on each wing extend to
their full travel positions.
When the Speedbrake lever is in ARMED position, thrust levers 1 and 3 are near
the closed position, and the main landing gear touch down, the Speedbrake lever
is driven to UP
position, extending all spoiler panels.
If the Speedbrake lever is in DN position with the main gear on the ground and
thrust levers 1 and 3 near the closed position, and reverse thrust levers 2 or 4 are
pulled up to idle detent, the Speedbrake lever is raised out of DN detent and driven
position. This provides an automatic ground spoiler function for RTO and
provides a backup automatic ground spoiler function for landing when the
Speedbrake lever is not armed during approach.
For go-around protection, if Thrust lever 1 or 3 is advanced from closed position,
the Speedbrake lever is driven to DN position. This occurs whether ground
spoilers were automatically or manually extended. The Speedbrake lever can be
manually returned to DN position.
The EICAS advisory message SPEEDBRAKE AUTO indicates a fault which
could result in the loss of the automatic ground spoiler function. If the Speedbrake
lever is in ARM position, the message indicates a fault which could result in
inadvertent spoiler extension in flight. No inadvertent spoiler extension can occur
with the Speedbrake lever in DN position. The spoilers can be operated manually."
What the speedbrakes do is to "spoil" the lift and put more weight on the MLG, thus braking efficiency is increased. At the landing weights for the 744 it's not a big deal. Some aircraft have a very "touch" armed position and having the lever in the armed position isn't quite there. If reverse isn't used then you have a situation where the spoilers won't deploy.
Bottom line: No big deal....