For 2.6, I set jar return to 0% gasp how dare I eat glass, m'realisms because the random return got more annoying than rewarding; my hoarder tendencies wound up feeling more frustrated that I had to find a spot for a single dang jar after drinking something in the middle of an immensely over-encumbered plundering outing inb4 first world problems. I don't think I'd play with any return % other than 0% or 100% just for that pack-rat reason - and I'll never not appreciate being able to customize that setting to accommodate personalizing my video game entertainment.
For dew collector vs water source harvesting, I only did jar-filling in the early-game; once I was able to afford/craft gatherers and tarps for 2+ dew collectors, I never filled jars at a water source again, because I was filling my time with other tasks. The nearest water was around 100m away, so it's not like access was an issue (and even if it was, buckets exist, which I did make use of in my short 2.5 run). Early-game, I was barely surviving on water (again, 0% return) and barely finding enough sand to get by, but as the run went on, a few things happened: 1, better-hydrating cooking recipes reduced demand for water; 2, better shovels eased sand-digging for stocking the forge (long before cement mixer); 3, water purifier helmet mod in loot, though I only used it 3-4 times.
When I left the Pine Forest, I hadn't used jar-filling for a while and had three dew collectors with tarps and gatherers which I was only just keeping stocked with jars. In Snow (I lingered in Pine a bit too long, so decided to move from Pine straight to Snow), I set four dew collectors on the roof; a while later, I got the water filter recipe, and now the four fully-upgraded collectors are easily exceeding the supply I need for glue and food. I might be fine with two, comfortable with three. I'm not even using the cement mixer to make more sand for jars, any pallet-sand just goes into the forge and there's still way more than I need.
Because I'm lazy, I don't jar-fill. Possibly, it could be more efficient to load twenty stacks of jars and shove them into a hole in the floor with a bucket's worth of infinite water - but jars are slow to craft (and my single forge is usually busy with cement or other materials) and the manual-refilling animation is so slow. I appreciate that it's slow, and that you can only fill 10 jars at a time- that feels like a good balancing decision in my book. Whether it was a conscious balancing decision or not, it makes manual-filling tedious and time-consuming- particularly when factoring in that in the time it takes to fill 1-2 stacks of jars on animation alone, I've already dumped my jars into the collectors on my roof and have moved on to other things, and can grab all that water off the roof in as much time as it takes to fill a single stack of jars.
Someone might use a dedicated second forge or tweak a faster refill animation or larger empty jar stacks to reduce the tedium of jar-filling, but they could just as easily tweak the collectors to perform even better - as they are now, though, the dew collectors feel like they scale by quantity, while jar-filling is metered by the time it takes to fill each stack. It feels pretty balanced... using the perspective of time efficiency, particularly for the lazy or frequently restless. That's me!