You said they were hurting at the end of last year's winter but how were they doing at the end of last year? Did they go dormant in autumn ok? Have they broken dormancy? I do not protect them here as my winters are mild and this year it was even milder. But since you are playing the odds, consider that you could still have a late frost. Do you think a late frost would hurt them a lot in the shape that they are now? A minor temp drop would be ok but some areas in the northeast got dumped half a foot of snow nearby. Check your average date of last frost to get a feel and consider in what shape you think the plants are for this season.

Sometimes the parts above the ground gets hit hard but, as long as the roots are mulched, the plant can regrow. Just water them before any temperature drops way below 32F (if the soil is not frozen) and make sure they have 2-4" of mulch. Do not fertilize after mid summer (once they are established, they can feed off the decomposing mulch... provided you maintain 2-4" of mulch year around and provided your soil is not sandy).

i do believe it would be time to unbury them .... you dont want an airless situation on the plant itself ...

but it might not hurt to leave the burlap itself for wind ...

when is you last frost/freeze date .. mid may like my z5 MI???

spring may be early.. but keep in mind.. ma nature is a cruel witch ... i never trust her ... lol ... no matter how tired i am .... of looking at burlap ...

ken

ps: i believe its called anaerobic .. lack of oxygen ... if your leaves crushed down it can create this bad situation .. it often depends on what type of leaves ... maple can be the worst ...

https://duckduckgo.com/?t=ffcm&q=anerobic&ia=web

https://duckduckgo.com/?q=anaerobic+mulch+problems&t=ffcm&ia=web

btw .. you dont have to remove the mulch from the protected site... just get enough out.. that the plant is free of it ...

Autumn seemed to be friendly, with moisture, etc., but the cold did come quickly. From my limited experience I would say the large-leafed rhodies went dormant well. The leaves I can see now look very healthy, especially on the large-leafed rhodies. The smaller leafed azaleas might have experienced a too-fast-and-hard cold snap in autumn. We'll see. Last frost date is in May, but I feel fairly certain I should't leave them covered that long.

I am using white oak leaves. They are like miniature plastic garbage bags. They can smother even the hardiest of plant underneath if not shredded. The leaves at the bottom are shredded, but I dumped more on top that were not shredded. I also used an eco-friendly fluffy insulating packing material than exists in sheets about 1" thick to line the burlap, and some to gently lay on top. I've removed that. I like that stuff so far as it provides some protection while letting air circulate very well. Collecting it for next year. Will remove some of the top leaves today.

Thanks for the advice. I should also have mentioned that one of my biggest concerns is wind. In winter the huge majority of the winds are behind us and broken by land features so we feel little wind at all. But, if it switches and comes from the south, beware. I had some seriously wind-burned az/rh last year! I am keeping the burlap up, especially that which protects the southern side. The oak leaves are my biggest concern now. I don't have any experience with winter protection!