Capping Buffs / Penalties

It's something of a meme, that certain character classes (*cough* bard
*cough*)are incredibly over-powered because - with sufficient buffs -
their skill set can be combined in ways that give them incredibly high
bonuses (buffs) to their die-rolls. For some, this is one of the
things that makes D&D a lot of fun, but these are the sort of things
that make me look at 'new D&D' as being almost comic-book superhero in
style; a far cry from the murder-worlds of classic D&D that were my
first (and favorite) experience with the game.

Of course, not all players will abuse the system in this way, and not
all DMs will be so lenient as to allow a simple dice roll to allow
patently impossibly results (there's a difference between letting the
players try anything, and letting them do anything just because
they've gotten a sufficiently high result on a die-roll.* But maybe
one way to avoid the problem is just to cap the bonuses (buffs) you
can attach to anyone roll?

In our campaigns, we already were sort of doing that, although it
still allowed some occasional disturbingly high bonuses. We divided
buffs into three categories: natural, magic and situational, and
decided that you couldn't apply more than +5 from each category to any
single roll. Natural would be anything integral to the character
(usually skill or stat buffs, or equipment); magic is anything from
spells or items, and situational would be any advantage you might get
from the situation you were in (for instance, leaping over a wide
chasm when there's an updraft might give you a bonus).

Our campaigns were fairly low-powered so we rarely topped out on all
three caps (+5 to +7 tended to be the max. I don't think we ever got
more than +10).

For fairness, it worked in the other direction too, though. Penalties
were limited to -15; -5 in each of the three categories. However, DM
Fiat allowed the Dungeon Master to just flatly forbid the success of
certain actions regardless of dice rolls.**

What do you think? Are you fine with RAW and uncapped buffs/penalties?
Or do you limit your players to (or are you, as a player fine with)
maximum buffs in your game?







* I don't care that you just rolled two natural twenties and have a
+14 bonus, you can't fly by flapping your arms really fast, Dave!
** I don't have to roll any dice for it, Dave. You can't catch a
castle!