Without intending disrespect, I'd have trouble accepting anyone has actually practiced spider fingers for five hours (collective time) over three days. It's a boring if useful exercise, so 10-15 mins max of it per session would be pretty 'had enough of that' normal. And I say that as an atypically disciplined and persistent individual.
Even if you used it for warm up on two sessions daily over three days, that'd still just be between a total of between an 60 to 90mins hands on at it. OTOH if If you really have done three hours hands on over that period, you should be starting to get it. Make sure you carry out hand and finger flex and stretch exercises first, then just persist. 10-15 min sessions reinforced a couple of times a day every day or every other day. That will get you there fastest.
Single fingers? No. Ke[u]ep at the progressive all fingers down-up discipline[/u]. It's a co-ordination & control motor skills exercise as much as a stretching and flexibility warm-up one.
Patience, persistance, time will get you there. Keep at it.
Keep moving on progressively with other lessons though e.g. chords, and come back to it for that 10-15min warmup each session. That's how you're supposed to use it.
Nothing to be dismissive about re 'entry level' guitars. With few exceptions they're more than adequate for that task today. Conventional Strat balance and body shape (thigh fit) ordinarily shouldn't be causing neck wrestling problems. You shouldn't have to press the guitar (body?) down with your armpit. More info req. Are you average height and build m/f or?