Hermes is a game and an art form. It’s not a logical mathematical equation where if purchases/time > x a buzzer goes off and a quota bag appears. There isn’t a set minimum package of items to buy to magic an offer. The only rule is that they expect you to be “a good client with a healthy profile” and the healthier your profile the better and quicker your offers probably will be.
The process is that a shipment comes in and the SM reviews the contents with the SAs. Some stores assign bags directly to SAs, others allow the SAs to pick based on what their known client is interested in. The key is to be the one on your SAs mind when a bag you would want becomes available. This is done through continual face time and purchases that put commissions into the SAs paycheck, plus general genuine kinship with your SA. The final hurdle is the SM reviewing your profile (and the profile’s of other interested SA/client pairs) to decide who gets offered the bag. This decision is usually more strictly monetarily based, however if your profile is decent and you haven’t gotten a quota bag for a few seasons, you may get some additional preference. SAs don’t typically nominate clients unless they have a pretty good feeling that the SM will agree, ie your spend meets the SM’s general preference of 1:1 or whatever it may be. These aren’t spoken numerical thresholds and it encompasses factors like length of profile, money spent, categories purchased, time since last quota bag purchase, etc. Luck in the case where it’s the end of a sales period or the store got a bonus shipment or met their sales quotas early or numerous other factors outside of the client’s control, can also help or hurt.
So yes, spending at least 1:1 for each bag is helpful, though not necessarily strictly necessary, unless it is. Hermes shopping should be fun and not an elaborate equation. Buy what you love when you see it through one SA as often as you can and the bag offers will come.