I think they can be dropped can't they?
Yes, of course, but normally in peace time they don't drop them because of the danger to people on the ground and of course the cost of recovering them and reshaping them and refurbishing them for reuse is high, so normally in peace time they don't drop them.
Su-25s often land with external fuel tanks attached.
In any case the use and discarding of EFTs is wasteful and forces the planes relying on them to dedicate their most capable suspension points to fuel rather than payload, effectively turning very nice looking payload capabilities in way less stellar figures in actual missions. With Flankers 8 t payload is the actual amount of weapons they can carry in real missions and that makes a big difference.
I would say the only time a Flanker would carry external fuel tanks is for ferrying... flying from one airfield to another in a transfer and they would not drop their tanks.
For an operational mission they would more likely not waste a weapon pylon and would more likely use inflight refuelling to get the extra range or endurance.
BTW nice photo... does anyone know what that thing in on the centreline rear weapon pylon between the two engines?
The wingtips have jammer pods, and then R-73 AAMs and then R-77 AAMs and the Kh-35 anti ship/land attack missile, then on the engine naccelle it looks like KAB-250LG bombs... the front wings are not the right shape to be Kh-38s...