Thanks for the advice! And by "sheet mulching", I meant the process of laying down sheets of cardboard to smother a large area of weeds/sod, and then covering that with a thick layer of compost, and then a layer of mulch (pine bark in this case) on top.

What is already growing there if anything? IME cardboard and mulch is superb if you are starting with bare ground, and may well kill off everything if left for a full season and applied thickly enough, but there are a bunch of plants such as deep rooted burdock and dandelions, some tree and bush seedlings such as oaks, and certain types of running-root grasses that are only slightly slowed down by heavy sheet mulching. So unless I am starting with bare ground such as under an area where hemlock or spruce were or in a recently bulldozed area, I either spray with a short-lived herbicide that won't be retained in the soil (read product labels carefully) or solarize the area for a season by putting down plastic, sealing the edges, and just letting the sun cook the area for the summer and then planting in fall, or renting a sod cutter and stripping the area. It sounds like a lot of work, but for me, prep ahead of time beats weeding a bed I've planted before being sure all the weeds were gone. Once I am sure that everything is dead, then I put down cardboard or several sheets of newspaper and mulch.

https://s3.wp.wsu.edu/uploads/sites/403/2015/03/newspaper-mulch.pdf

I have found them to be great in permanent ornamental landscapes, despite what the linked article says, based on a number of years of hands-on experience. But both I and sah67 use the sheet component as a layer under an organic shredded mulch which isn't what the article seems to mostly be discussing.

In addition to the problems cited above with using cardboard or newspaper there's also the reality of how much bark or mixture you'd need. For a depth of 1 foot you would need more than 8 cubic yards to cover an area of 250 square feet - expensive and labor intensive even if it can be dumped right where it's needed because it needs to be spread out. You're also not actually amending the existing soil. It will remain as is until the sheeting rots away and then will take many additional years for the natural process of soil fauna doing the incorporation. Like a great many tempting "labor saving" short cuts in gardening, this winds up being less efficient and much less effective for creating a good garden bed than doing the hard work at the start.

I typically put down a 6" layer of horse manure (lots of weed seeds), cardboard or 3-5 sheets of newspaper, and then cover with about 6"-8" of woodshavings from the family wood shop. This settles over time to more like 4"-5" since it is initially quite fluffy, and then rots fast enough so that the mulch needs replacing every 3-4 years in areas where the plantings don't shade it enough yet. I have issues with voles, but not any worse than areas that are totally unmulched; I am overrun with them regardless. I do almost no weeding as long as edging keeps weeds from growing in from the surrounding area and the plants seem happy. But I make sure that everything growing there initially is removed in some way before starting.