The only time I have seen any slide support used is on a Park Model on blocks or piers. Any RV on wheels is designed to hang or support the slides from the trailer itself. If you have a stability issues a set of X Chocks have been sucessful for some to take the wobble out of the tires.I found these work on Travel Trailers and don't forget chocking all wheels front and back, this prevents wobble front and back and using the stab jacks too.
I've always used them. It really helps stabilizing while its windy and helps with some of the bounce from normal walking.
I only use enough pressure to support and check them weekly or after a rain as I'm sitting on packed rock.
I recently read an article about using slide supports that made me change my mind on using them. RV manufacturers design their camper frame to hold the design weight of slide and occupants. The problem referenced in the article was the fact that the camper support jacks may drift down, or settle in the ground the pads are sitting on, and tires slow deflation/loss of air. Any one of these conditions will cause a stress on the slide mounting, with possible damage to the slide or camper. I get it you could adjust the supports periodically. It's the off chance that something occurs quicker than your adjustment schedule.
We have a 2019 Mallard 335. Work in Florida during the winter months and spend 3-4 months at one site. I bought a 3' level and use it when initially parking. We also use slide support jacks (with wood blocks) and will check the levels every 2-4 weeks. Never had any problems - yet...except for the slide wipers (Next big project)!
I had a recent problem with my main dining room hydraulic slide where it started making a pounding noise when going in along with the slide going in with great difficulty. A close inspection of the toothed rail's pass through the trailer frame showed that the welds for the supporting rollers that support the rack rail away from the frame cutout hole were broken in 2 places, and the toothed rail on the slide was rubbing and bouncing on the lower lip of the frame slide rail cutout. I figured out a way to place a 2 x 4 stud under the roller itself lifted up by a bottle jack on the ground to keep the rail's teeth from rubbing on the frame hole during slide-in movement. Luckily I had a brother Knights of Columbus RVer who is an expert welder come to my space 40 miles away from where he was staying with a welding generator the local church had for maintenance of its steel gates and handrails all over the church property. He welded up the broken places in the rail roller support attachments to the frame while I had the slide jacked up into proper position as described before. The slide now works correctly without physical support assistance.
I thought about the problem, trying to analyze what caused the welds to fail (short of poor quality welds). My analysis is that the roller support attachment welds are under minimal stress when the slides are in. When the slides are out, and I go to climb up on the roof for rooftop maintenance (this slide top is my easiest, lowest roof access) these welds are under maximum stress. Therefore, I have started doing this 2 x 4 stud / hydraulic bottle jack additional support under this slide rack upon space arrival after extending the slides, although the support welds have been repaired and no additional support is needed when retracting the slides.
I currently own a Heartland Mallard M335. I use supports on the larger passenger-side slide as it is a deeper slide, resulting in more mechanical downward pressure, and it is frequently bearing the weight of occupants in the recliners and/or dining table. I use the trailer mostly for snow-birding in Arizona for 6 months at the same park and site. I typically don't use the supports if I am doing short 1-2 week trips during the summer. I had a bad experience with my last travel trailer where the floor of the 'super-slide' literally separated from the wall on the end under the couch. I am a big guy - 6' 2" and 225# - but it still should not have caused that! I tighten the supports until just slightly snug using a short piece of 2×4 between the support and slide and check it on a regular basis for "snugness" as I do both of my stabilizers. It has the added benefit of substantially reducing movement of the trailer when someone is walking around. I am unable to use the between tire chocks as the M335 has the Wide Trax suspension and the distance between the axles/trailer tires is very wide, much wider than any screw chocks I have been able to find.