Well I don't make a purposeful mix, but I do use the compost as mulch, or mixed in. It could only help, I can't see a downside.

For many years I had no source of good inexpensive mulch and never enough home-made compost so once or twice a year I mixed my compost with sawdust and shavings (likely a mix of hard and soft woods) from a local mill. I used our cement mixer to more easily and thoroughly mix this and added various other ingredients depending on what was available such as old manure, leftover spent potting soil, and whatever type of nitrogen rich supplement I had such as blood meal or various seed meals. I also always used alfalfa pellets which dissolve fairly quickly in water in the cement mixer and I believe helped to color the sawdust.

I always used this as mulch, never mixed it with soil. It was a good way to extend and more evenly apply my meager supply of compost and the finished product looked better than pale sawdust.

I found that if I didn't use it right away the pile would quickly start to heat and sometimes I left it awhile before using. However used as mulch there were no negatives and it greatly improved my soil over the years.

You may find the addition of compost to the mulch will cause it to decompose faster but that IMO is not a drawback.

The first step is to have a good reliable soil test done and then look carefully at the growing conditions and what, if anything, has changed. Is the area shadier now then when these were planted, or is it more open, sunnier? Are those plants getting adequate moisture? What in the environment has changed?

I mulch all my plantings and beds with a horse manure/bedding compost then in places where I want a more finished look put pine bark fines/wood mulch as a layer on top. I don't bother trying to physically mix the two. It works great for me.

I've tried fall leaves on bottom and pine needles and shredded cypress mulch on top. In the warmer months of spring I will douse the whole area with bunny poo tea every week for 4-5 weeks, maybe every 6-8 weeks. I am hoping to get a compost-in-place type of result. I used whole leaves, after shredding lots of them and storing or adding to my compostumbler. If it doesn't compost in place as I hope, I'll add more shredded mulch if needed, eventually those whole leaves in direct contact with the soil, are going to last a maximum of 3 years. And with bun poo tea I would say max 2 years. The worms are likely to help with compost making.

I want to add that the above post, is what I have tried on one bed only, kind of an experiment. It is underneath a Quercus Prinus/Montana, an oak shade tree, that is still very young. It is about 20 ft tall, and I have some shade plants under it and want to make good soil for shade gardening under this tree, so acidic ammendments are okay, most of my soil is currently neutral as is.

Heavy, repeated mulching usually cures all micronutrient deficiencies. how much mulch are we talking about?

I might add that this is my profession at a customers home, not my personal yard so profit, efficiency, and all that come into play as well. At home I have alot more options because looks are not soooo important, there i can use "alternative mulches." at a customers house I have to maintain an exceptional appearance, aka serious
curb appeal.

we put down 2" of hardwood each year in may. i thought there was compost mixed in (and still do). but the coordinator here that orders the bulk mulch says it's supposed to be 100% hardwood. I was thinking about a 1:1 ratio, still 2" depth, of hardwood and compost mix.

By the end of the year, most of the mulch applied that season has decomposed or disappeared from raking, clean ups, cultivating, etc... leaving plenty of exposed soil so it's not like we pile on more and more each year.

no doubt the drought a few years back probabaly took a weighted tool on these shrubs since they are in constant competition for water with mature trees. so... if i improve the soil, i am helping it retain water, increasing the odds of survival

That sounds pretty good to me. I've used a lot of municipal shredded yard waste mulch, which is pretty much the same thing. The grass, leaves and other rapid decomposers break down in the mulch pile, so by the time I pick it up it's wood shreds and semi-compost. I've used this for years on perennial beds and the soil has improved a lot. By fall all that's left is the shredded wood.