Many builds use a 5-piece set that is completed by weapons on one bar. This means that swapping to the other skill bar results in loss of the 4 and 5 piece bonuses. While there exist several 5 piece bonuses that appear to be designed for this application, they are often paired with 4 piece bonuses that do not work well on a single bar. I think this is primarily carried over from when 2-handed weapons were considered one set piece, so bar swapping only resulted in losing the 5-piece bonus and keeping the 4-piece.

Probably the largest annoyance is when a set has a 4-pc Max Health bonus, since swapping bars makes you lose that health momentarily, effectively dealing around 1.5k damage to yourself. Similarly, Max Stamina or Max Magicka will bounce on bar swaps (assuming they are nearly full) costing you resources without even casting skills.

Beyond Max Resource bonuses it becomes a little subjective, but I feel like things like Penetration and Resistance would be best left to 2-3 piece bonuses, since these are typically built until they reach a set value (pen cap or armor cap), and ideally the same on both bars.

Stats like recovery, damage, and Crit Chance are more forgiving to being lost momentarily, and therefore make excellent 4-pc bonuses. Healing taken and received would probably fall into this category as well. These stats can be viewed as controlling the rate you do something (damage, heal, or regenerate resources), which is less noticeable when changing than stats that control the value of something directly (like Max resources, or to a lesser degree resistances).

I think the easy solution here is to simply rearrange some of the lower (2-4 pc) set bonuses to be more friendly toward running them on a single bar. Many are already set up like this, but for those that are not, I’d like to compile a list of recommendations here. Feel free to comment below if you have an idea for a set that would benefit from some rearranging. I’d like to avoid actually changing any bonuses (adding or removing) since ZoS seems to have these balanced as they see fit.

Edit: To be more clear on methodology, I wouldn’t care to even look at the 4 pc bonus on sets like Ebon or Twice Born Star, because the 5 pc bonus does not work well on a single bar. This is true to a lesser extent for sets like Necropotence and Plague Doctor.

I’m directing attention more toward sets that have a 5-pc bonus with a long cooldown and/or carries over to the other bar (such as Lich or Burning Spellweave, which both already have acceptable 4 pc bonuses for a single bar set).

Edit 2: The goal here is not to try to increase DPS or simply make sets better based on how bonuses are currently performing. For example, Spell Crit is often valued more than Magicka Recovery, but this is not enough justification to swap a Spell Crit to a 2 or 3 piece bonus and let a Recovery bonus fall off sometimes as a 4 piece.