The 20 - 25 insects a week is a maximum they should be eating in the warmest part of the year to avoid over feeding. Insect size would be about half the size of the lizards head. They could be feed on the higher side of the numbers if the insects are smaller. You are potentially giving her 15 insects a week and in the warmer months giving her meat as well. As your supply becomes the bulk of her food it become more important to supply a proper diet as she is less likely to get what she needs from the remaining insects she catches. If she becomes dependent on you then she may even go hungry if something stops you from continuing the supply.
You are probably doing her no harm in the short term and you both get something out of the arrangement. Just remember the closer you get to feeding her a full weeks worth of food she becomes more reliant on your supply. If she fills up on 'junk food' she may not hunt for variety and end up with vitamin and calcium deficiency, or she may continue to hunt and eat more than she should and become over weight with associated health problems.
I do love watching the wild life at our place and have used bird feeders in the past as I figured we have limited their food supply by building on their original habitat. Now I prefer to improve the habit I share with them by planting ground covers and plants that feed birds and lizards with seasonal flowers and fruit or attract insects. The population of Eastern Water Skinks have increased considerably since we moved here and if something happened to us or we move away the population should continue to thrive (unless new owners change things back to lawn and concrete or have predator pets like small dogs or cats.)
This was the reason why I only offered her small amounts of diced meat and other treats over summer and autumn, she was happy to accept these when she found them (a few times a week), and was very active in hunting down insects (mostly cockroaches under the furnature, we stopped placing roach baits and using surfac spray and flying/crawlng insect sprays when we became aware that Lizzy was visiting almost on a daily basis), and she did a great job of exterminating the roaches, demolishing some house spiders and gave the little ants that came into the kitchen a hard time).
It was only when Lizzy showed up in July after brumating for a few months I decided to get some mealworms to use as treats, and then some crickets as treats too. They've been a great means of building a very good level of trust between Lizzy and me and of building on my reationship with Lizzy. She LUVS them ! and now lets me tickle her under the chin or on the side of her head and neck, has ever gone hand surfing a couple times (when she climbed completely onto my open hand to take a mealworm and eat it there). She's very comfortable around me, not so trusting and comfortable of my wife - but at least she doesn't run away and hide whenever my wife comes into the room now.
I have never intended the mealwoms (or crickets sometimes) to be used as her only source of food. She is free to come and go as she pleases and I am certain she goes on hunting forays under the house and in the "wild" area under the bluegum .
This is why I never give more than 4 medium meal worms at a time, and usually only 2 or 3 even if she comes back for more and gives me "the stare". And this happens about 3 times a week at present. Lizzy seems content with that and will usually go for a patrol to check all the likely roach hiding places when she realises she'll get no more food from me and then comes back and hangs out on the top of the lounge or on the fax transformer for a while and has a siesta.
She's NOT 100% dependent on us for food, and I think she'll have no problem finding all the food she needs of her own accord if we go on holiday, being a wild lizard she will just revert back to totally wild and independent, unlike a lizard that's been bought and raised in captivity and never needed to find it's own food.
We're a retired couple (in our mid 50s) and have no desire to or plans of moving. AND she has in/out ways back out if the house is locked up so she'll never be trapped in a foodless house - some 3/4" holes I drilled for coax cable access from under the house about 20 years ago that are still there (hidden behind the furnature but accessible to her in strategic rooms will let her go in and out).
I too have a thriving and growing colony of EW skinks, and brown skinks and some bluetongues in my yard. (NO cat, no dog, but 4 dogs next door - the EW skinks and bluetongues have been seen raiding the neighbour's dog's dogfood bowls. And their dogs chase any EW Skinks that they see, but I'm told they aways get away from the dogs). I enjoy seeing the lizards doing there own thing in my yard and often see them having sun bake and siesta on the paths and on my front patio in summer.
ps
I noticed that the huntsman spiders are getting active again this evening when I got home after dark, saw a few prowling about on the boundary fence next to my driveway.
Spotted a roachlike bug, all wings with a body about the size of mealworm beetle on the wall next to my front door - saved it for Lizzy.
If she shows up tomorrow (was AWOL today, sunny warmish and not much breeze today so she's probably been outside instead) she'll get it offered to her along with the medium (very fat cricket) I thawed out for her today and I'm keeping for her.
Left the front patio light on and will see if I can catch a moth or two for her too later tonight. Lizzy will think all Xmas' came at once if I get a moth as well for her (will definitely have to offered from between my fingers else the roachybug and any moth with fly off.
Are mealworm pupae OK for eastern water skinks as a treat ?
Are mealworm beetles before they go brown and armour plated OK too ?
PS 2 :
Loved the bark roach (one with wings), I let it go about 2 ft away from her and it started crawling away and she really enjoyed chasing it and catching it and made short work of eating it. The legs made her nose tickle I think as she rubbed it on the fabric of the lounge after she'd killed the roach by bashing it up.
Discovered she likes mealworm beetle pupae, gave her one that had just formed, ate it with gusto.