Buffing is an Art more then a necessary part of questing.
What I have learned over the years of playing...
Some quests buffs are more beneficial then others.
Even before there was ship buffs House P and House J (with enough favor) could grant resistance and other buffs that were useful before enough equipment, levels could be gained to do them yourself.
Some examples of Over-buffing deal with three areas
1) Over Extended buff - when not needed
2) Over-use of short term (example Displacement) and temporary buffs (Stone skin)
3) Unnecessary buffs - from easy to understand they are not necessary Fire Resist when fighting Ice Creatures to harder to spot, such as Blur where some equipment negates the visual and others do not.
Over extended buffs are hard to get out of the habit of simply because people are use to extending them while come up the levels. Paying a nominal fee to get 10 minutes out of a buff is a good price, unless the quest or next shrine is less then 7 minutes away. Now its not always know how long between shrines and I understand Over Extended the first couple times, unless you are told. However, when buffing ask the question and save the SP if its not necessary.
Over-use of short term buffs. There are two types of short term buffs; those that have a short timer and those that apply protection until a certain threshold is reached. While it can be seen Blur is useful for everyone (or people wouldn't be slotting items with it on) Displacement is only good for those that get more swings/shots taken at them. It is also a good way to help the primary healer of the party by making the sponge harder to hit so the healing member of the party won't have to through healing that direction every 3 seconds or risk hearing whining about how bad they are at healing (all the while the rest of the party is sitting comfortably with more then 85% of their HP). Ideally Displacement should be used by the one/two that seem to be taking the brunt of the attacks. Quests Like Sins where ambush after ambush occurs it might be a good idea to use displacement on all members of the party - but only if each ambush is taking more then 30 seconds to clear. Stone skin is an up-to 10 HP DR per hit, Earth Savants can get more out of this, but still its best use is on those taking the brunt of the attacks. However, most of these types have innate DR already, so its usefulness begins to dwindle.
Unnecessary buffs are actually contributed by both the giver and receiver/requester. The giver for these reasons: Lack of Knowledge of what is actually needed, Lack of Knowledge of what other players already have or just an autopilot mentality of "I have the buff, and by golly your going to get it even if you don't need it"... The flip side is when a buff is asked for, that is not needed... Such as resists for stuff that does not exist in a quest. Displacement on a character that will spend 90% of their time hitting monsters from behind, physical protection spells like blur and displacement and stone skin when fighting 90% spell casters. Protection from elements when fighting against melee types that don't use elemental damage. Protection From Evil while fighting Eladrin. We that have buffs have done these things. But have we learned from them.
Those that are only the receivers of buffs in many cases don't care if you have SP or not - as 90% of the time it won't effect their fun... However, you as the buffer have the option. Don't go to the extremes of All SP for buffs to No SP for buffs. Find the middle ground - realize that some quests you may need to allot more SP for buffing while others you may find you don't need to buff at all. As a buffer take the time to examine (Z) other players look at the buff list. Be open to ask if anyone needs something and if its a reasonable request help them out.
These ramblings are only my thoughts based on 5+ years of buffing... Most of which was learned when SP potions were the nectar of the gods, money was tight so having scrolls/potions of any type was important. I like to think that I made every copper piece work for me during that time
For the love of Eberron, please do NOT give people Blur or Displacement without asking them first. You think it's going to save the Cleric SP? In fact you very well could have just been COSTING that Cleric 20% or 50% of their SP regeneration. For some folks, Blur is a debuff.
Oh, and a new player (your audience, right?) will go broke trying to pass out Stoneskin all the time.
A Rage and a nice Extended Haste are always welcome, though.
Lets see.. before I hit lvl 12 I'm not gonna buff you with anything. Why? Because you don't need it. Up to that point i'll just nuke everything. You may get haste and GH later and that's about it.
When I hit capstone I'm gonna ask you which buffs you would like because when playing epics ppl only need specifics and by that time I won't really care about my blue bar.
XO, Darth