The shimmering is proportionally more shimmery.

Can he keep going on? Regardless of the answer,Temple will take another break, do some house chores (which he really should figure out how to do with magic) and come back maybe forty minutes later to cast it.

He can, in fact, keep going on!

For how long? After a minute or two he will put the thing down and do his chores.

He can go that long.

Cool and what happens when he gets back and casts it?

Stronger spell! Noticeably so!

Temple makes a celebratory dance, it goes on for a while.

Okay, he will try the TFWS again, but he will try to "push" the extra kick for thirty seconds, stop for ten seconds then try pushing it again for another thirty seconds and cast it.

Tug.

Temple's new nemesis, the tug!

Well, he will have to wait. Sigh.

He spends this time productively by thinking of new test ideas, especially revisiting failed spells that might work better with the new trick.

He waits about an hour before casting that scroll again.

Not as strong as when he'd spent two minutes charging.

Still, that is evidence he might pick up a scroll later and charge it with extra-power. Oooh, maybe he can figure out how fast he recharges or at least how long each spell baseline costs in terms of minutes.

Temple will try to do just that. First step, is creating a scroll, for flight if he has enough mana for that, maybe TFWS if he doesn't, then he will spend the mana until he feels the tug. Does this step work?

It does! And he can spend about twenty minutes dumping power into the scroll before feeling a tug, except the tug happens way too fast for him to really notice it while he's dumping the mana and oops the scroll is soaked through and turned into sludge.

Ew. He cleans up. At least it didn't explode or anything, which is a sign that scrolls can be damaged without causing something weird. Still, what a waste.

Well, Temple will wait about a minute before trying writing a TFWS scroll, he will pay very close attention for that tug. If a minute doesn't cut it then he will wait for another minute, and so on, moving to five minutes intervals after five minutes of failure.

After the second five-minute interval he can do it again.

Yay! He tries again after six minutes and then waits another minute if it fails, until he can figure out where exactly between five and ten minutes it fails on.

Somewhere between seven and eight, apparently!

Temple rubs his hand gleefully. Some laughter might be involved. He will repeat the process with just the "Wind!" spell and then Flight, followed by Telekinesis.

Wind takes about two minutes to recover up to, Flight takes half an hour, Telekinesis almost an hour.

Any difference from "Wind" if he tries "Water" or "Earth" instead?

Water and Earth seem to cost the same as Wind.

Temple will see if casting spells interferes with recovering the "mana" by casting Flight and seeing if he can cast "Wind!" Two minutes after that.

He will need to wait a while to recover enough to cast Flight, and will not have recovered enough to cast Wind two minutes after having done that.

Will he be able to cast it at all while Flight is active or he will only recover after that spell expires?

Only after the spell expires, as it transpires.