Extending the flaps close to the limit speed does cause wear on the flaps, but under normal conditions you should be 10 to 15 kts below each limit speed anyway.............not a problem.
99% of the time I never need speedbrakes to slow while configuring unless caught out, they are not necessary.
CX used to say not to use flap 15 or 20 to slow the aircraft on the GS, they said use the speedbrake instead but that seems to have gone now.