It's all about the recipient's wallet type. Before multipath payments, we were usually stuck to something like 1/10th to half a bitcoin, max, on most routes, but technically up to 10 BTC on routes that we knew were going thru someone with a ton of liquidity and no one else. (Rare)

Nowadays we can stack quite a few routes at once so 10BTC wouldn't be a problem on most routes. Still, the receiver's end can cause a bottleneck because they often have hosted wallets that open small channels for them. Wallet of Satoshi, for example, won't open a channel with 10BTC in it for every customer for obvious reasons. Even if you run your own node, do all of your channels have 10BTC stacked together to receive that much in? It's pretty uncommon for all but the largest companies with fat channels to spare.

So the bottom line is to ask your recipient if they have the channels to handle the amount you want to send them. If you're sending it to yourself for some reason, you have to set up the channels first and that can take a while to find that many channel partners.