I have been tiling for 35 years ish and I learned with sand and
cement. Solid be is achievable with adhesive with or without clips.
I have used a few types apart from the PLM but all seem to do the same job (even the lash clips when used with enough adhesive) I don't always use the clips especially when the floor is flat and the tiles are flat.
I did try some of the Mustang clips that Andy Carroll is touting and those clips performed very well and were not expensive like the Raimondi clips.
I have also tried some from Bright Ideas as a test and even they were pretty good but they were the cheapest I have used. For porcelthin jobs I would use the Bright Ideas clips and for stuff 10mm thicker I would use the Mustang, if needed.